The Ultimate Guide to Pool Water Balance

It really is a balancing act – to maintain the correct levels in the pool water. If pH or Alkalinity is too low, or Calcium Hardness levels are too high, there can be problems.

Other pool chemicals also must be balanced and in a certain “safe area” – an ideal range for each component of water balance that is tested.

Pool water quality is affected by the level of pH, which is affected by Alkalinity. Pool water pH levels that are too high can cloud the water or create scaly deposits, but low pH levels allow for pool equipment and surfaces to become etched and corroded.

Adding too much chlorine can cause skin and eye irritation. On the other hand, when levels of sanitizers are too low in a pool, they will not provide the power to kill algae, bacteria or other contaminants.

Water Balancing chemicals are important because they prevent damage to the pool, or poor sanitation from chemical levels that are too high or too low.

Chemistry of Water Balancing Chemicals

Water balance for pools essentially means to bring into balance, the most important being the pool pH, Total Alkalinity and Calcium Hardness levels.


POOL-WATER-BALANCE-PH

pH measures the acidity or basicity of the water. The pH scale goes from 0 to 14, and 7 is considered neutral. Anything under 7 is acidic, while anything above 7 is considered basic. Pool pH of around 7.4 is best.

Pool water pH values below 7.0 creates a corrosive environment, or an acidic condition. Add a base to bring the pH up, into a more basic range to prevent corrosion.

pH levels in the pool water have ideal range of 7.4 to 7.6, and whether higher or lower, it’s not good for the pool or swimmers. At levels above 7.8 only 50% of your chlorine will be active.

Pool pH that is above 7.8 creates a scaling or basic condition. This means that scaly deposits may form, or cloudy water problems. High pH also reduces chlorine potency. Add an acid to bring down the pH to prevent the formation and build-up of scale.


pool-water-balance-ta

Total Alkalinity measures the hydroxides, carbonates and alkaline substances in the pool water. A close cousin of pH, Alkalinity buffers your pH, keeping it more stable. When TA is too low, pH levels are erratic, and not stable.

Raise low alkalinity by adding a base to the pool, specifically products labeled Alkalinity Increaser. TA levels should be 80-120 ppm. Total Alkalinity strongly influences your pH level, so if your pH is off, be sure to check the alkalinity.

Lowering Total Alkalinity by adding an acid to the pool water. This is harder than it sounds, because it also lowers pH levels when you add acid. Certain types of acid will lower Alkalinity more than pH, but it can still be a process of lowering TA, raising pH, lowering TA, raising pH…


POOL-WATER-BALANCE-CH

Calcium Hardness measures the softness or hardness of the water. Hard water has higher calcium or magnesium content. These particles can deposit themselves on pool surfaces, lights and ladders, or can frequently come out of solution making the water cloudy.

Calcium Hardness is another important factor to any pool. Water can get murky and scale formations can occur as well as stains. It is important to keep calcium hardness levels below 400 ppm, but the most desirable range is usually 180-220 ppm.

When calcium hardness is too low, add Calcium Increaser. The water is then too soft and can corrode surfaces in the pool. If levels are too high, scale deposits and cloudy water can become a problem.


What’s Temperature got to do with It?

ducky-pool-thermometer

The Langelier Saturation Index can be calculated by testing water for pH, total alkalinity, calcium hardness, cyanuric acid and, temperature. When water warms, from 70° into the high 80’s – this changes the way water balance components interact.

Generally speaking, higher water temperatures makes your water more active, and is balanced at lower levels for TA, CH and pH. When water temperatures are cooler, higher levels are recommended.

The Saturation Index uses a temperature factor to tell you the ideal levels for TA, CH, Cya and pH. The math is a bit complicated, and involves charts, but Pentair has an easy to use online Saturation Index Calculator.


Other Pool Chemical Levels

Full analysis would include testing for Total Chlorine and Free Chlorine levels, and for Cyanuric Acid levels in the pool.

POOL-WATER-BALANCE-CL

Free Chlorine is the amount of chlorine that is available to work with, not including Combined Chlorine, or chloramines. When you test your water with a DPD test kit, you can test for Free Chlorine (FC) and Total Chlorine (TC).

Subtract FC from TC, and you get CC, or combined chlorine. When CC is over 0.3 ppm, it’s time to shock the pool to remove these contaminants. Free chlorine levels should be at least 1.0 ppm.


POOL-WATER-BALANCE-CYA

Cyanuric Acid retains the chlorine in the water for a longer period of time. Stabilizer is added to some chlorine to protect from breaking down – which occurs from UV rays. When the pool stabilizer levels are low, your chlorine won’t last as long.

The ideal range is 30-50 ppm, and better on the low end as new research suggests that high levels of Cya can suppress chlorine activity and potency.


POOL-WATER-BALANCE-TDS

Total Dissolved Solids is another important factor to pool water balance, although it is not often tested unless pool water conditions have become unmanageable. When water evaporates, minerals are left behind – and as evaporation continues, the water becomes more saturated, which makes it harder for chemicals to be successful in their endeavors. This in turn gives pool stains an opportunity to come out and appear in the pool.

The only way to lower TDS is to drain some water out and add fresh water. Recommended levels for TDS are less than 2000 ppm, or 5000 ppm for pools using salt chlorinators.


BONUS POOL WATER BALANCE TIPS!

  • Test 2-3x per week, adding adjustment chemicals as needed.
  • Run the pump after adding chemicals, to help distribute.
  • Add one chemical at a time, or add them into different areas.
  • Test and adjust in order. First alkalinity, then pH, then calcium.
  • Use the Saturation Index to consider water Temperature.

taylor-dpd-cl-br

Pool chemical levels can be crucial to the health of swimmers, as well as the health of the pool. Unsanitary water, stains and corrosion are common in pools with consistently unbalanced pool water.

To avoid these problems, test and balance your pool water regularly, and enjoy your pool with less mess, and less stress!

122 thoughts on “The Ultimate Guide to Pool Water Balance

  1. Michael Spino

    We had our in ground pool refinished and HP installed December 2019. I’m in Florida and Temps were in the 70’s when done. I can not get the balance any where near normal since. TC=0ppm FC=0ppm pH=8 TA=175ppm CH=750ppm Stabilizer=100ppm TDS=1400. Water Temp = 88 degrees I have been spending a small fortune every month trying to get this balanced. I never had this problem with the old pool finish. I have drained 1/2 the water (12000 gal total pool size) and got the calcium down for about a week and then it shot right back up.I’m at a loss as to what to do. I’ve done Acid, Metal Conditioner, Stabilizer, Liquid Chlorine, and chlorine tablets. Every other week when I test Calcium is always high, and everything else is totally out of wack! I need some educated suggestions

    • Just focus on the pH and chlorine for now, keep dumping in acid every day if needed, to get that under control and below 7.6. Add enough chlorine to get a reading, just keep adding until you break thru!

  2. Michelle Sharp

    Is there a good time of the day to add chemicals…morning, evening, or night? Thanks

    • Hi Michelle, not really. Many people say to shock in the evening, so the sun won’t destroy the chlorine too fast, so it has longer to work, but other than that, no…

  3. We have an above ground 17×48 pool. Using an Intex same filter. pH is in range but on the higher side using chlorine tablets. Water was crystal clear during the early season. But the water temp has increased and water has turned cloudy and has a green tint. When I shock it or add chlorine it turns a darker green. When I remove chlorine tablets it gets lighter green and hazy. I’m at wits end. Thought about draining and replacing same and starting over. What can I try instead of starting over. By the way I’m on well water with medium hardness. Any suggest will be greatly appreciated!

    • Hi Micah, these could be minerals and metals, green colors are usually associated with copper. Have you tried using a sequestering agent, to lock the ions in-solution? Products like Stain Away, Metal Free, or Jack’s Magic The Blue Stuff for Vinyl Pools, add an initial dose then maintenance doses, usually weekly. As you mention, you can also drain and replace some water, but unless you are filling from a truck, the same problem will occur. If you have a home water softening system, it may be filtering much of the minerals and metals, and if you connect a hose to the system, you will get better water to fill the pool with, than when using the outside spigots, which normally are not connected to the home water treatment system.

      • Thank you for your feedback.i put some algae killer in it yesterday and today it’s spotless. Is it possible that I had an algae bloom?

  4. Barbara Sims

    Hi… we just had a pool installed (above ground) and we are having trouble keeping the PH 7.4-7.6 (it is staying at least 7.8) and the chlorine goes from high to almost non-existent. Any suggestions?

    • Hi Barbara, I have a lower pH preference, being that chlorine has much greater ‘efficacy’ at lower pH levels, or has more potency. So you are right to be concerned. 7.8 is the upper limit, so try to lower it. There may be a reason, are you using liquid chlorine? It has a very high pH level, or there may be some leaf debris that is high pH. For the chlorine, you may need to check the Stabilizer level, aka Cyanuric Acid, to be sure that it is 20 ppm minimum, to protect chlorine from the sun, or maybe just use more. As water warms in the summer, more chlorine is needed, and less is needed in spring and fall, when water temps are lower. ONe more thing, since you are lowering your pH regularly, be sure to monitor total alkalinity, which is also lowered by acids, it may need to be increased with sodium bicarb aka Alkalinity Increaser, to maintain a minimum 80 ppm level.

  5. What does it mean when my TH is 0 my TC is 1 an my FC is 0.5 ?

    • Hi Kurt, not sure what TH is…? But if Total Chlorine is at 1.0, and Free Chlorine is 0.5, that means that CC (Combined Chlorine or Chloramines) is also at 0.5, as TC = FC + CC. And, it’s generally thought that at CC levels greater than 0.3 ppm, one should shock the pool to break apart the chloramine bonds. Add 1 lb of shock per 10,000 gals, with a pH level of 7.0-7.2 (for most potency).

  6. my head is spinning,all these chemicals i dont know what to add or how much its a real headache,you can read the test dip stick but it doesnt tell you what you need to add or how much

  7. Hi I have a 14 feet round pool that is 42 1/2 deep.
    My CI Br is orange when tested and my ph is red both are high.
    when the alkalinity is tested light green after the five drops of the indicator. I add the alkalinity titrant drops it does not turn red. It turns to blue at 12 drops. I then did the total hardiness test; I add the 5 drops of the hardiness indicator and it turns yellow.

    • Hi Justina, that could be a result from either the high chlorine or high pH or both. If you have a Taylor test kit, you can use reagent #7 (R-0007) to remove chlorine in the sample before testing. Also try to lower the pH into range, or below 7.8, before testing

  8. Please help! 16,000L above ground. The chlorine gets eaten up, even after a shock treatment. PH is always ways too high even after adding ph minus. Everything else is at a good level. Help!! We have algae and I can’t get rid of it!

    • Hi Lora, I would say… More pH Down and More Shock! Check Alkalinity too, it may be very high or very low, thwarting your efforts to adjust pH. Try to get pH level to 7.4-ish, then add a triple dose of pool shock, 3x your normal amount. This will usually destroy whatever is consuming the chlorine. You may also want to use AquaChek Phosphate test strips, or have the water tested, to see if you have a phosphate problem (over 300 ppb).

  9. We just installed a brand new pool. Chemicals went in today and we are running pump on filter setting. Salt went in as well as no one told me to wait till water was balanced. Chlorine generator is off.
    How long should I run the pump for after a brand new fill and will adding the salt too early mess anything up?

    • Hi Trina, no problem adding the salt early – you do want to start chlorinating the water, so why wait? Chlorine must be in the water constant and consistent, all day and night. When chlorine approaches zero, that’s when things begin to grow and bacteria can flourish. Filtering is also very important for clean and clear water – every day, not a single day off for your overworked filter! 🙂 Depending on how effective your filter is, and on how warm the water is, and on how high the chlorine level is… you need between 8-24 hours per day of filtering. Most people run their filters about 12 hours per day, but you may need more or less, depending…

  10. Opened pool yesterday. Added 3g of liquid chlorine. Ran pump 24hrs. White mold is present. High PH and Low Chlorine. Question, do I shock pool now or level pool first?

    • Hi Mike, always balance the pool before shocking, especially the pH level. A lower pH level makes your chlorine much more potent, for a more effective shock treatment.

  11. Mike Becker

    I drained our pool and have refilled with well water that is pretty hard water. What is the process to restart the balancing of the water? I drained to lower the CYA.
    Thanks for your help!

    • Hi Mike – copied this from our eGuide: Pool Startup chemicals https://www.intheswim.com/eGuides/pool-startup-chemicals
      New Pool Start Up: Chemicals for starting up a new pool, or an older pool that has been drained and refilled is not very different than those chemicals needed for pool opening, only that you may use more of them.
      Tap water usually makes pretty good pool water in most cases. The pH and alkalinity are normally within a good range, but depending where you live, the water hardness can be too soft or too hard. It’s quite important to test pH, Alkalinity and Calcium Hardness levels with a reliable pool test kit or strip.
      Well water, when used to fill a pool, can have a good water balance right out of the ground, or in other cases it can require a good deal of adjustment to pH, Alkalinity and Calcium Hardness. Minerals, metals and hardness are usual concerns with well water. Consider filling with well water that has been filtered and treated by the home filtration system, rather than using outside spigots.
      When filling a pool with high calcium hardness levels, minerals or metals, or suspended solids, use a pool pre-filter to improve water quality and trap stain causing material before it enters the pool. Especially recommended for new pool plaster start up procedures.

      Step 1 – Add Stain & Scale Treatment First!To protect pool surfaces, use a non-phosphoric sequestering agent, (Stain & Scale) to keep minerals and metals locked up in solution. It’s important to add this chemical to the pool first, even as the pool is filling. Allow the agent 4-8 hours of filtration to make all of the chemical connections before adding chorine.
      Step 2 – Water Balance: When a pool is refilled with fresh water, the first step is to balance the pH, Alkalinity and Calcium Hardness levels. If you’re lucky, they may all be within range, but in most cases, at least 1 of the 3 will need adjustment. Add water balance chemicals needed to the water with the filter running, and use a pool brush to help disperse quickly.
      Cyanuric acid levels will be zero in fresh fill pool water; you’ll need 4 lbs per 10,000 gallons of stabilizer or conditioner to raise your cyanuric acid levels, which protects chlorine from degradation by sunlight.
      Step 3 – Add Algaecide: We’ve skipped over shocking the pool, and unless your fill water has poor clarity or a strong chlorine smell, there is probably no need to shock the pool. And if you don’t add granular pool chlorine, you can jump right ahead to adding pool algaecide to control and prevent algae from establishing a foothold if chlorine levels should dip, or filtration problems occur.
      Step 4 – Add Chlorine Tablets: Without delay, add chlorine tablets to your chlorine feeder or chlorine floater to continuously chlorinate the water. You may need more tablets than usual at first to build an initial residual, and after that about 2 tabs per week, for each 10,000 gallons of pool water.

  12. I have been checking my Acid level and is coming up with a color that’s not on my chart more of an Orange is color closest to 7.2. What do I need to do.

    • Davy Merino

      Hi Marty, assuming that the test kit reagents are not expired or exposed to heat/cold – if you can rely on them and the pH seems low, add some pH increaser to see if that raises the pH level.

  13. ralph hudgerson

    I have just finished resurfacing my 20,000 in ground pool with diamondbrite. How much of what chemicals do I need to add to start off.

    • Hi Ralph, first balance the water for pH, Alkalinity and Calcium hardness. How much you need depends on what your readings are to begin with… Once balanced, if you want to protect the bright white color, you can begin using a sequestering agent, such as Metal Free, Super Sequa-Sol, or our own Super Stain Away to lock up minerals and metals in solution, where they cannot stain the pool. These chemicals degrade with sunlight however, so regular maintenance doses are also needed, added as per label. And, maintaining good chemical balance always, is very important to protecting the appearance of the new plaster, to prevent stains, scaling, etching and deterioration.

  14. What does it mean if my chlorine, pH and TA readings are ok, but my Total Hardness is 0 and my cyauric acid is way above the 30 to 50 range? Im using test strips for these readings. How do I correct this?

    • Hi Renee, it is unlikely that Total Hardness is “0” – although it may be lower than recommended levels. Low hardness can cause issues with plaster and vinyl surfaces, and can make pool water cloudy and foamy more easily. Add Calcium Hardness increaser to raise hardness, however another test is in order, perhaps with a different test strip or test kit. Cyanuric Acid (aka Stabilizer or Conditioner), when above recommended amounts, this makes chlorine lazy and inactive, and when over 100 ppm, can make it hard to maintain a level or get a reading. Dilution is the Solution, for high CYA levels, draining and refilling with un-stabilized water from the tap. You can also use Bio-Active, cyanuric acid reducer. But again, a retest would be prudent, to be sure of the levels. Maybe a pool store test, or you can buy the same test kit the stores used, Taylor K-2005, for $75.

  15. I have And 8 foot round above ground pool filter 15 inches high so around 500 gallons of water I shocked it 12 hours ago with 1 pound of chlorine. My levels are free chlorine -10
    alkalinity -0
    pH -9
    and total hardness-0
    My filter pump is working great but my water is very milky looking

    • Hi Lois, those chemical levels are likely incorrect. Your water must have some hardness and some alkalinity, no? I suspect a bad test or expired tester. pH of 9 is very high as well, which makes your chlorine nearly ineffective, and your water unsafe for swimming… Maybe go to a pool store for a free water test, and possibly pick-up another test strip or test kit to compare.

  16. Hello,

    I have a 14 ft round above ground pool that is 42in deep. Total chlorine and free chlorine are perfect, total hardness is fine and ph is at 7.1-7.2
    But the total alkalinity is low as well as the stabilizer. What should I add

    • Hi Alicia, your pool should have around 3500 gallons. Raising the total alkalinity is simple, add one cup (8oz) of Alkalinity Increaser for every 10 ppm needed, to reach 100 ppm. For stabilizer (aka cyanuric acid), add 5oz of stabilizer for every 10 ppm needed, to reach 30-40 ppm.

  17. Bob Evans

    Good morning, I am struggling with are pool it is a 4,500 above ground, I have a HTH test kit, my chlorine is off the charts the test color is orange, the ph is low very light purple, I have shocked the pool, the water is very clear, doesnt burn your eyes. I also have a sand filter pump. not for sure what to do, do I need to to take the floater out?

    • Hi Bob, yes you can remove the floater, and the chlorine level will deplete over a few sunny days, no problem.

  18. L. Gomez

    I’m new to this pool maintenance.
    My pool holds 20,000 gallons and has a DE filter. I’m in southern CA (hot summers)
    My free chlorine is 3
    my ALK is 180
    my ph is 8.4
    my CYA is 150

    I add acid correct? but how much?

    • Hi there, based on such a high cya level, and the very high alkalinity and pH, if it was my pool, I would drain and refill. If you cannot drain and refill at least half the pool, then yes add acid to lower the pH and alkalinity and use Bio-Active to try to lower the cyanuric acid level below 50 ppm. High cyanuric acid makes your chlorine very slow to react, and you will have trouble killing bacteria and algae. Add 3 quarts of muriatic acid or granular pH decreaser to lower pH and alkalinity. You will then likely have to raise pH a bit higher, which will raise alkalinity again, so you’ll need to lower the alkalinity again, which will raise the pH level, continue in this manner until alkalinity is below 120 ppm, and pH is 7.2-7.6. So if you can – drain the pool, but if that is not possible – plan on spending some cash on chemicals, and some good time correcting the situation, and possibly dealing with sick swimmers.

      • L. Gomez

        I just refilled the entire pool in December/January ( California tap water) of this year. I added 1 pound only of conditioner and while I do use trichlor tablets, especially in warm weather, mostly i chlorinate with liquid chlorine and occasional shock with granular chlorine. How did CYA get so high in such a few months time?

        • If you just refilled and only added 1 lb (which will only add 10 ppm in 10000 gals of water), and have only used tablets for a few weeks or a month – I would suspect that the test for cya may be false? Test again, if using test strips, they can be rather inaccurate on cya tests – a turbidity test is best.

  19. Davy,
    I’m having a problem keeping my PH and TA balanced. When the TA is at 80-100 the PH wants to stay at 7.8-8.2. If I add acid to lower the PH to 7.4-7.6 then the TA goes down. So its a battle of constantly adding acid and Baking Soda. I’ve found that if the TA is at 60 then the PH stabilizes at 7.4-7.6. Is it OK to leave the TA at 60 in order to keep the PH stabilized?

  20. Diane marrama

    My ALK & PH are in range but CI=0 TCI = 0 and HA = 50. Water is cloudy. I have a salt water pool. What should I do?

    • Hi Diane, add calcium hardness increaser, to raise calcium levels to 200 ppm, but before you do that – add granular or liquid chlorine to raise the chlorine level to over 10 ppm. Salt pools will need to add chlorine to the pool from time to time – despite claims that ‘you’ll never have to buy, touch or store chlorine again!’ – there are times when you will need to use packaged chlorine – on pool opening and closing, for algae or cloudy water, for a powerful shock treatment, or if the salt system is having problems.

  21. Rose Mary

    Very new to owning a pool… our test strip shows
    Hardness – very low
    Total chlorine – very high
    Free chlorine – very high
    pH – very low
    Total alkalinity – very low
    Stabilizer – low
    Where do I start to get my pool water right? The water is blue, but slightly cloudy.
    Any and all help will be greatly appreciated! Thanks!

    • Hi Rose, just keep filtering the water, 24/7, all day and all night. Add calcium hardness increaser to raise to 200 ppm, then add alkalinity increaser to raise to 80 ppm, and the pH should also raise-up somewhat. Add stabilizer if the level is below 20 ppm, otherwise it’s ok. As chlorine comes down, keep adding so it won’t go to zero, but keep it on the high side, until the water clears. If still not clearing after several days, check into the filter, may need new sand or new cartridge.

  22. My balances are good except for my calcium hardness, off the chart, very hard. I am on a well, so draining and replacing some water would do nothing. Should I be concerned from a health standpoint? Equipment is replaceable. Have you any suggestions for softening this water?

    • Hi Wendi, no health concern, the concern is scaling deposits, or cloudy water. Softening the water is not possible, unless you fill the pool from the home water softener system. Using Stain & Scale chemicals will help to keep the minerals in solution, and prevent some of the problems, but must be used consistently, added every week or two.

  23. Mrs Ripps

    To say We are having trouble balancing our pool is an understatement. The water is continually cloudy although with 24/7 filtering it improves but as soon as we add any chemicals the cloudiness returns. We had issues with staining, used ascorbic acid which removed the stains but now seem to have issues with copper returning. Swimmers getting green hair and water going blue! When backwashing water is also blue. pH is low, Chlorine low because of ascorbic acid treatment, alkalinity low, cyanuric acid high. Want to add sequestrant to remove copper but need balanced water.
    Just don’t know what to get right first!
    Help!!

    • Hi, if possible I would drain some water, and refill with fresh, to both lower the cyanuric acid level to 30-40 ppm, and to remove many solids choking the water. As it is refilling, add the sequestrant and raise the pH and alkalinity levels to normal. Keep a 2-3 ppm level of chlorine during the process, and begin filtering 24/7 again as soon as it is full. If the copper source is an old pool heater that is no longer used, bypass the heater with a bit of plumbing modification.

  24. I’ve added borax and baking soda to adjust my balance. Pool is 27,000 gallons. How long does it take for the readings to be accurate. (how long should I wait to retest)?

    • Hi Lisa, I am unfamiliar with the use of borax and baking soda treatments. TFP will have information on that.

  25. My pool was very low on chlorine – free and total – and I finally succeeded in getting it in the normal range with shock plus tablets plus granules. Alkalinity and stabilizer showed normal range when chlorine was low.

    Now it’s swapped. Chlorine total and free looks good – hardiness okay – but ph/total alk/stabilizer all very low. Question – can I add base (baking soda) and stabilizer at the same time? Or should I add one and wait and retest? Which first?

    • Hi Sophia, I would add the baking soda if below 80 ppm, and then check pH a few hours later and add pH increaser if needed. Alkalinity and Stabilizer don’t fluctuate too much too quickly, usually, so I wonder if one of the tests was wrong – especially with cyanuric acid (stabilizer), best to double check to prevent adding too much. Chlorine tablets also add a bit of cya to the water, so if one starts the season with 20 ppm or so, they may end the season with 30-40 ppm. So I’d let the stabilizer ride for a few days, and test again.

  26. Connie Watkins

    Hi Dave! Your expertise is needed! I have had a pool for many years, almost 20. Currently I have a 30 foot round with almost 24,000 gallons of water. Everything is in working order. I am usually in the good with chemical levels and have crystal clear water. However, this year we went straight from cold to HOT weather, add on not having time to dedicate as much time to opening the pool as I normally do. Anyhow, my water turned green from the git go. In the beginning I definitely had algae, but kept adding the ph and alkalinity along with shock to kill the algae, including algae killer. I currently have all levels at the right levels but the water is still green. I had to add a metal remover first to get my chems to stay vs. being “eaten up”. My sister is having the same issue. Where do we go from here?

    • Hi Connie, all you need to kill algae is a good (low) pH level 7.2-ish, and lots of chlorine – depending on how green it is (?) – you would either do a single shock, or a double shock or a triple shock, which is 1 lb, 2 lb, 3 lb’s of shock, per 10,000 gallons. For light green pools, 10 ppm is usually enough, use 1 lb per 10K, medium green, hard to see the floor, use 2 lbs, dark green cant see the floor, use 3 lbs, or even 4 or 5 lbs per10000 gals sometimes – keep adding it until it turns a blue-ish color, without a hint of green, then add a little bit more. For your pool size that’s 3, 6 or 9 lbs of shock, all at once, until it magically blues up before your eyes, within minutes.

      Now the second part of the equation is filtration, and if your pool filter media is tired, weak or old, or if the filter is on the small side, that can create some problems for fast clean-up. First off – run the filter non-stop, 24/7, it won’t blow-up, I promise! Keep a clean filter but don’t over-clean it, let the dirt and algae build up a bit. For cartridge filters, adding a cup of Dicalite powder is a good filter aid, or sometimes a new filter cartridge is needed to clear up the water completely. For sand filters, Dicalite can also be used, or Pool Alum (aluminum sulfate flake), just a cup, or the Slime Bag is a good product to help out small sand filters. Replacing filter sand would also help cleanup, FilterBalls have been reviewed with success on our blog for a pool your size. Filter Cleaner may be needed, before during or after, and Clarifiers can also be of help, added 24 hours after shocking the pool hard.

      Final part is clean-up, vacuuming, brushing, skimming and rechecking water chemistry, and keeping chlorine levels high for a few weeks, to prevent rebloom. If struggles with algae continure, you can test for phosphates, you may have a need for phosphate remover.

  27. Hi Alex,
    We feel like we’re spinning our wheels every year on chemicals and can never get it balanced well or for very long! Currently the hardness is ok-high, the chlorine is very low, the pH is very low-ok, the alkalinity is ok-high and the stabilizer is low. Since we have the alkalinity “close” to being ok, do we start to increase the pH? Should we also increase the chlorine at the same time? Thanks for your help!
    Nikki

    • Hi Alex, the situation you describe is not perfect, but not that bad actually. Low pH has the advantage of more active chlorine, as long as pH is at least 7.2 it’s OK, it’s just a problem when it dips below neutral 7.0, into acidic range of 6.8 or less, that concerns about vinyl and plaster and chrome pop up, all the soft and shiny surfaces. High calcium is normal, nothing you can do about it really. High alkalinity is usually fine, up until 140 ppm+, where pH control gets a bit wonky. The only thing that really concerns me is low chlorine / low stabilizer. Stabilizer is good from 20-50 ppm, and chlorine should always be minimum 1.0 ppm, and up to 3.0 ppm. 1 lb of stabilizer will raise cya levels by approx 10 ppm, per 10K gals.

  28. Nancy Cee

    We just opened pool ; water is green, nowe added clarifier, chlorine and algacude-and stabilizer- we have foaming, my husband is getting more frustrated by the minute- we had drained 1/3 of water down at end of season and replaced 1/3 at start of season- what can I do to help him- he is ready to close it! He is so upset after all the scrubbing and work; today our skimmer is covered with slime ! Help! This is first year we had this!

    • Hi Nancy, I’m sorry for all that trouble – especially on father’s day! The foaming is likely coming from the algaecide. If the pool is still green, I would suggest shocking the pool heavily, with 2-3 lbs of shock per 10000 gals, with a suitably low ph level 7.2-7.4. Filtration is a big part of any difficult water clean-up, sometimes new filter sand or filter cartridge is needed, and almost always, running the filter pump 24/7 is needed until the water clears. Good luck!

      • Sharon Jerome

        Hi Davy, my pool is clear, I’ve been running the filter 24/7 for about 3 weeks. I have shocked it. Added baking soda, algaecide and stabalizer plus conditioner. The water still isn’t balanced, I only have the test strips so I don’t know the actual numbers but the ph and alkalinity are good. Free chlorine is good. Hardness is low, total chlorine is high and stability is low. Can we still swim in the pool like that or is it dangerous to? Thank you and happy father’s day! Sharon

        • Hi Sharon, sounds like you are almost there! For water sanitation, or healthy water, focus on pH and chlorine level. If you have a good chlorine level of 1-3 ppm, and a good pH of 7.2-7.6, and the water is clear… you can assume is would be safe for swimming. If the chlorine is 5.0 – 10.0 ppm, it may be good to avoid swimming until it drops naturally lower, removing some chlorine tablets if needed. Although it may be safe and sanitary, it could cause skin irritation and dry hair, or bleach swim suits.

          Calcium hardness is not really a health concern, but if too low, it can cause some surface problems, staining and some issues with foaming or even cloudy water. Low stabilizer (aka conditioner, or cyanuric acid), is only a problem for bright sunny pools, that have trouble maintaining at least 1 ppm during the sunny parts of the day. Shady pools can run with a lower cya level, 20 ppm… but higher levels of 30-40 ppm may be needed for pools that get a lot of sunshine.

  29. Mary Jane wills

    My pool is 24×52 just switched to sand filter – My chlorine is slightly low and ph slightly low – Can I add your super pool shock to deal with both ?

    • Hi, a low chlorine level makes for potent chlorine, but too low could harm the pool liner. As long as you are above 7.0 – no problem. Best pH level (IMHO) is 7.2 – 7.4. The pool shock will raise chlorine level, but will not affect pH very much. If below 7.0, add pH increaser. For daily chlorination, using tablets in a floater or chlorine feeder, is best to maintain a consistent and constant chlorine level. Use shock to superchlorinate every few weeks, to remove any pathogens that have escaped normal chlorination, to zap contaminants, or to remove chloramines (chlorine byproducts) and if algae or cloudy water is visible – but otherwise use tablets for a slow and steady chlorination, rather than peaks and valleys of chlorination.

  30. anthony catapano

    my ph alkalinity and stabilizer are all low. What should i Add?

    • Hi Anthony, pH and Alkalinity are related, so I would add Alkalinity Increaser to start, to raise Alk to 80 ppm, which will also raise the pH level. For stabilizer, you can add cyanuric acid to the pool. For dosage amounts, consult the package labels or you can use poolcalculator.com

  31. Heather LaFriniere

    New pool owner! I have a 24 foot by 48 inch round pool with a sand filter system. We recently filled our pool and I have low chlorine levels with high ph and alkalinity as well as 0 CYA. Am I correct in saying that first I need to balance the alkalinity then the ph and then worry about the chlorine?
    Any advice is appreciated.
    Thanks!

    • Heather that is the usual method, however, don’t let the pool go cloudy or green waiting on water balance adjustments – it’s just that chlorine is much more effective when pH/Alk are in line…

  32. Bren Mancini

    Fiberglass /Salt/water volume 19500
    FAC 1
    TAC 1
    Salt 2600
    CYA 40
    TA 100
    pH 8
    Acid demand 2
    Copper 0
    Iron 0
    Pho 500
    Should I’ve adding dry acid to Pool if my TA is good at 100?
    Also my ichlor was at 78 when company came to open pool and 1st water test for FAC was 10 and so was TAC so I dropped the ichlor to 20 now we are at 1 do you recommend going up alittle on the ichlor ? ( pools salt/chlorine dispenser )

    • Hi, I like a 100 ppm Alkalinity level, no need to lower it. But pH of 8.0 is destroying half of the chlorine created by the ichlor, as it is listless and useless at higher pH, yet active and potent in the 7.2-7.4 range. For your chlorine level, 1 ppm is the minimum level for pools, you may be good there during cooler months or weeks, but should need to raise it in warmer temps, or after rain storms, or periods of heavy pool use, to compensate for the degradation to your chlorine from sun, debris, water temp and bather load. Your phosphate level is not super high, but 500 ppb is over the point where you should want to use a phosphate remover, probably before it gets really warm this summer.

  33. Great information. I have a bit of an Issue I cannot solve. My TC is measuring at 2 and my ph is at 7.2 and my total alkalinity is measuring at 240. I have tested multiple times. My pool is also very cloudy, I cannot see the bottom, its about 33250 gallons. I got it cleared up a little bit last week by adding acid and then after some raining I shocked it and it got cloudy again. Just added more DRY ACID tonight at 60 OZ everytime I add it. I just am having trouble lowering the ALK. I heard about aerating while adding the acid to keep the ph up but my jets do not reach the top of the water. I do have a slide though I can turn on which would add some air nicely. How do I lower the ALK and make the pool clear again?

    • Davy Merino

      Robert Lowry has a great article about using aeration to increase pH. The slide would help a little bit, also you can use this $25 fountain that connects to a wall return to help aerate. The idea is that you need less pH increaser after lowering the Alkalinity. If you can get Alkalinity down to 150 ppm, you should be OK. Keep at it! Clarifier and extra filter runtime can help with the cloudy water.

  34. […] week, or the pool just isn’t clear without regular shock treatment, you may look at your water balance, circulation or filtration – there may be performance issues there, requiring more pool shock […]

  35. April Ramsey

    HELP! We just got our liner replaced and it is amazing how quickly our pool turned a dark green. Cannot see the bottom. We have had such poor experience with taking our water to a commercial pool store that I determined I would do it myself, but I am completely overwhelmed. I bought a home test kit and my readings are Free chlorine 0, Ph 7.8, Alkalinity 80, Hardness 0, CYA 40. I should add that it is a salt water pool and we have not added salt back yet. Also, we did put 3 pounds of shock just because we were hoping it would attack the green monster! We added that yesterday and it looks basically the same today. Any pointers will be greatly appreciated!! Feel free to speak to me as a child…I am a pool novice!

    • Davy Merino

      Hi April, first get the pH down to about 7.2, by adding a pH decreaser (an acid), about 4 cups or 32 oz dry measure, then retest. High pH makes chlorine ineffective and algae loves it – the calcium hardness cannot be at ‘0’, so that should be retested, but not a huge factor in cleaning the algae. CYA 40 is perfect – to protect chlorine from the sun. Alkalinity of 80 is also perfect. So, just lower the pH, and add another 3 lbs of shock afterwards, and run the filter all day and night. Be sure the filter is doing it’s job, many algae problems are related to poor filtration and circulation. Good luck!

      • Christine

        Just a little formula I’ve used for 17 years and it works 99% of the time. 1lb of chlorine treats 10,000 gallons of clean water. If your cloudy double that formula. If your green triple that formula. Easiest way to clear a pool with algae issues unless the culprit is phosphate. Which is commonly misdiagnosis

  36. Mrs. Richter

    I have a 12,500 gallon pool that is over run with algae. It’s so bad that you can’t see the bottom. My husband and I both (unknowingly) shocked the pool and now have an extremely high chlorine reading. When the water test reading should be yellow, it’s turning ORANGE. Our PH is over the highest mark on our testing kit 8.0 and the TA is 70. HELP!

    I’ve added about 3 lbs of TA to raise the Alkalinity in hopes to bring the PH down. I will retest in 24 hours.

    What’s the best way to lower the Chrorine so we can do a Flock Treatment on the Algae? Do we need to drain some of the water and add fresh?

    • Davy Merino

      Hi There! It happens, we all make pool mistakes! The first thing to do is to lower the pH, by adding an acid or pH decreaser such as muriatic acid, or our granular pH reducer chemical, sodium bisulfate. For your pool, you would add 28 oz of liquid acid, or 3 cups (24 oz) of dry pH Reducer, to lower from 8.5 to 7.5. To Kill algae, you must have a low pH, so if needed, continue to lower the pH into the 7.1-7.2 range. In some cases pH will go so high, it goes off range, as you mention, so you don’t really know how high it is, so test again every few hours, and add more if needed. TA of 70ppm is a bit low, and adding this acid to lower the pH will also drive your TA levels even lower, so later after the algae is dealt with, you may need to add more TA increaser to come up to 80-90 ppm. Now, once the pH is back normal, assuming the pool is still greenish and chlorine level has come down very low, you could shock the pool again with 2-3 lbs of pool shock, and then if you want, a floc treatment liquid or granular, to sink everything to the bottom for vacuuming, to waste. Now, (only) if it is easy for you to drain a portion (1/4-1/2) of the pool, and refill Quickly – within 24 Hours, then it may be worth it, especially when the pool filter is undersized the media is older, it can make tough algae recovery faster and easier. But not for chlorine removal, that will come down over several days on its own.

  37. I have an 18′ X 48″ salt water pool that became overrun with algae when I was away. I have gotten it under control but now can’t clear the water up or get the balance right again. Right now my levels are as follows: Hardness, 500, Chlorine, 0, Free Chlorine, 0, Ph, 7.8, TA, 240, and Stabilizer, 0. The pool water is very warm, probably around 100 degrees f. As recently as a week ago everything was pretty close to good except for free chlorine levels, which were low. There are frequently a lot of people using the pool and I live in Mesa Arizona so it is always in direct sunlight. How can I maintain the correct levels of everything in my pool. I also need to add 2 more 40lb bags of salt.

    • Davy Merino

      Hi Jeannie, sorry to hear of these troubles. OK, first thing I would do is drain half the water and refill the pool, to get cleaner water with less hardness and alkalinity, if possible. If not possible or desirable (Hi, Arizona), then I would first attack Alkalinity and pH by adding pH decreaser repeatedly, over several days, and up to a week of adjustments, to get pH around 7.3 and Alkalinity down to 100 ppm, or as close as you can get it. Concurrently with the pH/alk process, shock the pool with enough liquid or granular pool shock to turn the water blue-ish, and then add a little more. Also should add 2 lbs of stabilizer (Cyanuric acid) per 10000 gallons, to protect chlorine from the sun. Keep hitting the pH, because a high pH level will make the chlorine sluggish and less effective. Check pH, alkalinity and chlorine every day and make adjustments as needed. Also, start running the filter 24/7 if you aren’t already, (it won’t blow up), and backwash as needed. When the water finally starts to clear, brush and vacuum, and then you can add an algaecide, if you want to have some preventative measures in place – but to clear a green pool you don’t need algaecide, it’s all about low pH, high chlorine and good filtration. And in your case, you need to lower the Alkalinity, in order to get your pH stable, where it won’t rise quickly again.

  38. Hi … I have a 10×30 pool and I am getting the following reading with my test strips.

    FCl 0
    Alk 80-120 ok
    pH 9.0 high

    There is a chlorine tablet in the pool. How can I lower the pH and bring up the free chlorine levels?

    Thank you so much.

    • Davy Merino

      Hi, pH is too high for the chlorine to work, it needs to be 7.2-7.4 for best results, as chlorine becomes very sluggish and impotent at pH levels over 8.0 – use pH decreaser to lower the pH level, and then you should start to see a chlorine residual with your test kit. You may want to shock the pool with granular chlorine, immediately after lowering the pH, to prevent algae and hazy water, and to raise chlorine level fast, then tablet(s) can be used to maintain. Use poolcalculator.com if you want to know exactly how much pH decreaser to use, it’s not much – in a pool so small, maybe 1 cup and then retest.

  39. Hello Guys, I’m new to pools we recently installed a 45,000 Liter Fiberglass pool. I’m having a hard time grasping the pool balancing act. I have a Astral EQ25 that automatically detects both Chlorine Levels and pH. Finally happy with the pools after changing some of the settings. Had my water tested the other day.
    Total Chlorine 1.0 (Its winter over here so no one is using it)
    pH 7.4
    Hardness 158
    Alkalinity 38

    So I purchased some Alkalinity Increaser and now ph is 8.4 after adding kgs in a bucket and mixing with water while adding onto pool.

    Seems to be a viscous cycle, any help would be appreciated.
    EQ25 has Salt Chlorinator Cell and Self Dosing Acid with probes.

    Thank you in advance.

    • Davy Merino

      Making big changes to Alkalinity is a bit of a viscous cycle, yes. But it will end, after a few cycles of raising Alk up, then lowering pH, raising Alk up, lowering pH again… until you get it right. When adding the pH decreaser, broadcast it, or pour it widely around the edge, instead of adding it all in one spot. This is supposed to have less effect on alkalinity. Because, as you know, when you add the pH decreaser to lower pH, it will also lower the Alk somewhat. Keep at it, you’ll get there. The self dosing acid may causing the problem, perhaps a probe sensor is dirty, or is causing the problem in some other way, constantly lowering your pH, which hammers your alkalinity as well…

  40. Krista Mcmanus

    We’ve had a lot rain lately and my pool is cloudy, greenish color. I’ve vacuumed it and added chlorine tablets, algae liquid, shocked it, still not clear.
    Readings are:
    0- free chlorine
    Ph- 8.4
    Total alkalinity- 240

    • Davy Merino

      Hi Krista, first thing to do is get the pH/Alk down and the chlorine up, right away or things will get worse. Add 2 cups of acid, or a pound of dry acid to the pool, per 5000 gallons, to move from 8.4 to 7.4. Your test kit may not go beyond 8.4, so it may actually be higher, and the high alkalinity will resist changes to the pH, so you may have to treat several times to see a solid effect to get pH down around 7.4 and alkalinity down below 150 ppm. In the meantime, add more tablets and more shock chlorine to keep some sanitation going on, and once the pH and alkalinity are lower and stable, shock it hard with 2-3 lbs of shock, per 10000 gallons. Run the filter 24/7 until resolved, it’s hot out!

  41. Hi i tested my 20X12 semi-inground SWG pool usingColorQ pro-7 and got the following readings
    FC 7.87
    TFC 8.79
    PH 7.4
    ALY 107
    CH 89
    CYA 60
    salt 3400 PPM
    question my water is starting to give off a strong chlorine odor is this ok or am i doing something wrong? BTW the temp was at 80 degrees and the water is perfectly clear.
    Thanks
    naz

    • Hi Naz, the difference between total and free chlorine is enough to warrant a good shocking – from your first two results, (TC-FC=CC), you would have a good reason to shock the pool. they say, to shock the pool when the the difference is 0.3-0.5 ppm – between total and free, basically if the sample darkens at all, that indicates the presence of chloramines, and you vnearly 1.0 (0.92) ppm of chloramines. Shock the pool to 10-15 ppm, using 2lbs of pool shock, per 10K gals. That should take care of the smell, and destroy the chloramines, which should be shocked to 10x – 15x the chloramine level, for effective and complete removal.

      • Thanks for the quick reply… can you recommend a good shock to use? oh and one more question i’m using Hayward AQ-TROL-RJ and it’s set to 60 ppm do think i should raise it?
        Thanks
        naz

        • Hi again, Cal hypo shock would be good choice. You mean it’s set to 6.0 ppm (not 60) I suppose, I would lower it to the 3-4 ppm range, no need for the extra chlorine, it just makes the salt cell work harder, and idle chlorine more readily turns into chloramines…

  42. Trudy Pridgeon

    Trying to get my chlorine levels up. After shocking twice and keeping 2 tablets going – level is still 0. Other readings are PH 7.8, TA 180, TH 400, CYA 70. From reading your article looks like my TH and CYA are off. Would that cause the chlorine to be 0? If so, how can I get the chlorine level up? My pool is 15′ round, 4 foot deep. Thank you so much for your help!!

    • Hi Trudy, try a double or triple dose shocking, try 2 lbs of shock. An unrelated problem could be the high pH/Alkalinty, not so much hardness and cyanuric actually which normally is good up to 100 ppm, or even a little more. First, I would lower the Alkalinity, which will take several attempts. Add 2 lbs of pH decreaser to your 5K gal pool, to drop pH level to 7.0. Pour the dry acid into a bucket of water, and then pour into the pool, in one spot, with the pump off for 10 minutes. Turn the pump back on for a few hours. Then raise the pH back up again by adding 2 lbs of pH increaser, directly to the pool, broadcasting over the surface or pouring along the edge, with the pump running. Repeat the process again after a few hours of circulation, and brushing the pool. Then test alkalinity and pH again. Repeat again as needed, over several days sometimes, to bring the Alkalinity down to around 100 ppm, which will then allow you to adjust the pH level to a more chlorine friendly 7.4.

  43. Hello,
    I have a 2,750 gallon above ground pool with a PH above or at 8.2. I’ve been adding dry acid but the PH won’t go down. My Alkalinity is 110ppm and my CL Br is like 0. My pool went from green to cloudy, bought a new filter and nothing. I’m very confused as to what steps to take.

    • alkalinity of 110 ppm is not too high, so it shouldn’t prevent pH adjustment, but may take a few tries. For your size pool, to go from 8.2 to 7.4 should take about 7 oz. of dry acid or 5 oz of liquid, a very small amount in any case. Very high chlorine would / could give a false high pH test, and when tested, the sample may bleach out, first showing color, then turning clear within seconds – if that is happening, it could be interfering with the pH test, making it appear falsely high. But since you say you have no chlorine in the water, then… try again on the pH decreaser. Your pH may be actually 9.2, but it can be hard to tell what it is when it goes off the scale…

  44. Tom Jackson

    Chlorine 3/6
    PH 8.4
    Total alkalinity 240
    Total Hardiness 100
    Cyanuric acid 100

    Water is a bit cloudy and ambient temp is 100F. Since acid is already too high, how do I get the water back in check? Pool was emptied and refilled about a month ago.

    • Wow, that’s messy! First drop the pH and alkalinity into range, by adding several gallons (depending on pool size) of muriatic acid or pH decreaser. Add the pH down with the pump off, and pour it under-water (not splashing along the surface, but gently underwater). It may take several treatments to lower the Alkalinity to 120 ppm, and then your pH will be very low, so raise it up with pH increaser, which also may take a few treatments. When pH is 7.4 and alkalinity 120 ppm, you can then adjust your calcium hardness, by adding calcium increaser, to raise it to 180 ppm. Cyanuric acid is also way too high – twice the limit. Ugh – if possible you may want to drain the pool again, is your tap water this messed up? Maybe drain half the pool, refill and try again – should be cheaper and easier than the alternative, or maybe not if your tap water tests poorly.

  45. Lowell Wallace

    have a 10 x 30″ pool filled up 2 days ago was told to add
    1lb of your pool shock
    just tested the water and found that my
    FCI = 10
    ALK = 0
    PH = 6.2
    WHAT DO I DO NOW?
    Thank you for your help

    • Hi, the water is very acidic, don’t worry it won’t burn your face off – but it is not good for the vinyl liner. If Alkalinity is really zero, it will be hard to maintain pH, as alkalinity has a ‘calming effect’ on pH. You may need to also add some Sodium Bicarbonate (Baking Soda), aka Alkalinity Increaser. For your very small pool, which only has about 1200 gallons, you don’t need much. Try using the Poolcalculator, to help you determine how much of a particular chemical to add. By my calculations, you need about 1 lb of Baking Soda, and 2.5 oz of Ph Increaser. Start with the baking soda, just pour it in, and then test pH and Alkalinity after a few hours.

      • Hey there, my alkalinity and Cyanuric acid levels are both too high! Should I empty the pool half way and refill? I wanted to swim today :/

        • Hi Brandy, that would be the fastest and easiest solution, to drain half the pool and refill. Test your tap water first though, just to be sure that it’s much better than the pool water, which is probably is. Alkalinity can be lowered with an acid, but it also lowers pH, and can take weeks of see-saw adjustments sometimes. Cyanuric Acid has a new reducer product called Bio-Active, but results are mixed, does not seem to work consistently for everyone, but claims to lower cya by 50 ppm (for each $50 treatment).

  46. Hello I have a 20′ pool round by 4′ deep. I just filled it with water 2 days ago. My chlorine level is at 0, the alkalinity and ph are very high. What can I do? How safe after adding chemicals is it safe to swim. Should I add the chemicals at night?

    • Hi Maria, first get chlorine in the water right away. Tablets will take too long to dissolve, add granular shock, just 1 lb, or 1 gal. of unscented laundry bleach. Then Lower the pH and alkalinity first, by using a Dry Acid, or muriatic acid, to 120 ppm maximum alkalinity, and pH of 7.2-7.6. Dropping your pH low, will also lower the alkalinity. For your size pool (7500 gals +/-), add 1.5 oz of Dry Acid (Ph Decreaser) to the water, per 0.1 reduction in pH desired. For example, if it’s above 8.4 (off the scale), then add 10 x 1.5oz. or 15 oz (1 lb.) of pH decreaser to lower pH from 8.4 to 7.4 (10 x 0.1). If Total Alkalinity is very high, it will cause the pH to resist the change, and re-treatment with slightly larger dose(s) may be needed to see full effect Wait sveral hours between treatments, and retest the water. After confirming lower pH and Alkalinity levels, you may want to do a proper shock of the pool, with 2 lbs of shock, or 2 gallons of bleach, and immediately add chlorine tablets (3-4) to a chlorine floater or a chlorinator installed on the pipe. Test daily for chlorine and pH until you develop your system that keeps a constant and consistent 2 ppm of chlorine in the water, and a proper and steady pH level. If your pool is sunny, adding 2 lbs of stabilizer (cyanuric acid) will help protect chlorine from the sun, and lower amount used, saving money on tablets. Other Tips: Run the filter longer than you think necessary, 12-18 hrs daily, to overfilter the water, especially now (July/August) when it’s hot. Keep the pool clean, skim, brush and vacuum as needed. You may find benefit from using a clarifier to help your (possibly) small filter, and algaecide to help your chlorine, if you spot any green or yellow algae at any point during the summer.

  47. Lori Romano

    I’m confused we have a 15 x 48 round pool. Added chlorine, PH is down, put in PH increased & still not right. Vacuum everyday, missing something.Water is clear. Thank you, Lori Romano

    • Hi lori, it could be a high alkalinity that is not letting you adjust the pH level. Check the Alkalinity level to see if it is 80-120 ppm. Or maybe you just did not add enough pH increaser.

  48. New pool owner and I’m confused with the whole chemical thing. We purchased a 12×39.5 bestway hydro force above ground pool. My chemical leaves are all over the place.
    Bromine 10
    Free chlorine 3
    Total alkalinity 0
    Ph 7.2
    Total hardness 0
    I know I’m missing something..I believe it has to do with the alkalinity? How can I keep the chemicals balanced and what am I missing as of chemicals? I have only got stabilized chlorine and concentrated liquid algaecide. The water is clear but I know I’m missing something

    • Davy Merino

      Hi, if you are using chlorine, there is no need to test for bromine. And your alkalinity and hardness – can’t be zero, well I suppose it could… but not likely. alkalinity should be a minimum of 80 ppm, and calcium hardness a minimum of 180 ppm. there are increasers available for both, if you need to raise the levels. It’s possible that they need boosting, or they could be high enough already, a different test kit or strips can be used to test again. Some pools do need only chlorine and algaecide, or just chlorine and shock. You may find a clarifier useful, if your water starts to look hazy. Having shock chlorine granular on hand is also useful, if algae is spotted, or to boost low chlorine levels quickly, or after a big group has used the pool, and water looks hazy.

  49. Hi. My pool has been very cloudy you can not even see your feet. My ph is 6.7 and my alkalinity is about 60-70 ppms. The chlorine is 3-4. We changed our sand and vacuumed the hell out of it. Don’t know what to do.

    • Davy Merino

      Hi, first you should raise the pH and alkalinity, at the same time, using Alkalinity Increaser. Raise Alk to 100 ppm, then if pH is not at least 7.2, raise it with pH increaser. Secondly, add a dose of clarifier to help coagulate small particles into larger, filterable clumps. Third, run the pool filter 24/7, or nearly 24/7, until water clears. Keep the chlorine level high, 3-4 ppm is good.

  50. Hi. Can you tell me the difference between balancing the chemistry in a Salt pool vs. a Chlorine pool?

    • Hi – good question. No difference, at all. pH, alkalinity and calcium hardness (and cyanuric acid) are all adjusted the same way, and to the same levels.

  51. pool opened, green water. How to proceed?

    • Hi, first thing is to check the pH level and adjust it if needed, to around 7.2. Assuming that your filter is already operating, the next thing to do is to vacuum the pool to waste if possible, to remove as much material (algae/debris) as possible. Once as clean as you can get it, recheck the pH and shock it with enough pool shock to kill the algae. Generally this is about 30 ppm, but it varies according to how dark green the water is. It goes something like this:

      • Light Green: 2 lbs shock per 10,000 gallons
      • Medium Green: 4 lbs shock per 10,000 gallons
      • Dark Green: 6 lbs shock per 10,000 gallons
      • Very Dark Green (with 12″ visibility or less): 8 lbs shock per 10,000 gallons

      These are general guidelines, but basically just keep adding shock until the water turns a blue/gray color, if there is any hint of green, add more. Shock in the evening, after the sun goes down. Then brush the pool to distribute. The next morning, you should have a chlorine reading. If the chlorine level is zero, you missed the mark, and may need to shock again, to completely overpower it.

      Run the filter 24/7 until it clears, you can add clarifier when the chlorine level drops below 5 ppm. If you can drain a portion of the water easily, you may also consider draining a foot or two, and refilling, before you begin treatment.

  52. How can I get my chlorine levels. Up? 4 floating basket, 6 lbs of shock. Water is crystal clear. All other levels are on level. Chlorine registers 0.

    • If you test strips or reagents are accurate, then either the chlorine demand is higher than the amount added, or the sunshine is burning off the chlorine as it’s added because of no stabilizer, or the level of stabilizer is so high (cyanuric acid) that it becomes hard to see a reading. If cyanuric acid is a good level (not too high or too low), and you say water is crystal clear… I might suspect nitrates or phosphates, use a phosphate remover. Or sometimes there is some unknown contaminant consuming chlorine, and it just takes a hella shock (5-6 lbs per 10K gals) to break-it down.

  53. Jeff Forbes

    My Ph is at 6.2, my free chlorine is at 10+ and alkalinity is almost 0……….pool looks beautiful but know I have issues. Suggestions on what I should do greatly appreciated. My pool is 16×32 and 9 feet deep end 3 foot shallow end……….

    • Davy Merino

      Hi Jeff, add Alkalinity Increaser – if at zero, you need 12 lbs. per 10,000 gallons of pool water (your pool should be about 20K gallons). Then see where your pH level is, after confirming that your alkalinity is at least 80 ppm. Chlorine should drop by itself.

  54. Oscar Ocampo

    In what order do you balance the pool water?

    • Ah, that’s a good question – start with Alkalinity, then pH, then Calcium hardness, then cyanuric acid (stabilizer) – and then adjust chlorine levels, or add any other chemicals used (algaecide, clarifers, stain & scale).

      • M Wheatley

        how much time between applications should one allow before testing again…. an hour, two, three???

        • Hi – for liquid chemicals, an hour is probably sufficient. For granular chemicals, I would give it longer, 3-4 hours, to fully distribute.

  55. […] Cut corners in this area and you could end up spending more on chemicals attempting to restore water balance and fight water […]

  56. […] sure that your pool water is balanced, sanitary and well filtered, so that you can be reasonably sure that no germs are in the water. […]

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