Swimming Pool Water Balance Problems

pool-water-balance

As a pool owner, you know how much change occurs in your pool constantly, due to various chemicals, oils and swimmers.

Because your pool water is in a state of constant change, it is essential to check and balance the pool water levels.

Regardless of type of pool – commercial or residential, and no matter what size pool you have – a large community pool or a small above ground pool, all procedures are the same.

Simply put, Water Balance is the relationship of the different measurements of chemicals combined in the water. Precipitation, pollen, pollution, bather wastes and windblown dirt and dust are some of the inputs that cause the water to be in an ever-changing state. These inputs alter the water chemistry of your pH, total alkalinity and calcium hardness.

pH-3

The pH level is the measure of how acidic or basic the water is. It’s a scale of 0-14, 7.0 is considered neutral. To put it in perspective, acid rain has a pH of about 4.4. The human eye is about 7.3, within the range of 7.2 – 7.6 that we use for pools.

alkalinity

Total alkalinity measures the hydroxides, carbonates and bicarbonates.Total alkalinity is recommended to be kept in the 80-120 parts per million (ppm) range for concrete or gunite pools, and 125-150 ppm for vinyl, fiberglass or painted pools. Alkalinity should be tested on a weekly basis.

hardness

Don’t worry if your hardness is under 500 ppm. Anything significantly higher than this can cause scaling and cloudy water, or calcium crystals that deposit as small clumps. Low levels (<150 ppm) are also bad, and can corrode pool surfaces; pulling out calcium. 200-400 ppm is an ideal range for your Calcium Hardness level.

WATER BALANCE PROBLEMS

Now you may be asking, what are some symptoms of common pool water balance problems? How can I know what is possibly wrong with my pool? What can I look for?

pH: If your pH level is too low, this means your water is too acidic, and you risk damage to the pool surface and corroded metals. Acidic pool water also leads to pool stains. Acidic water irritates eyes and skin, and allows for a faster evaporation of chlorine.

When your pH level is too high, this makes your chlorine weak, and provides an ideal environment for algae to grow. It also makes it easier for calcium and carbonates to precipitate out of solution and make the water cloudy, or leads to scaling and crystalline deposits on the pool or in the pipes.

For pH, the ideal range to keep is between 7.2 and 7.6. In The Swim has both pH reducer and pH Increaser for adjusting pool pH levels. Keep both on hand, even though you may need to use one more than the other.

Alkalinity: When alkalinity is too low, you may begin to see corrosion and staining. Since it’s closely related to pH, low Alkalinity will cause your pH level to be erratic and inconsistent. This is known as “pH bounce”.

High total alkalinity (TA) makes it hard to adjust your pH level, and make it stick. The pH becomes resistant to change when TA is too high. This can also lead to cloudy water, green water and swimmer skin/eye irritation. You can also see damage to filter cartridges or grids.

Alkalinity ideally should range from 80 to 120 ppm. Alkalinity Increaser is used to increase levels of alkalinity in the pool, but to lower total alkalinity, you add an acid, or pH decreaser. Lowering TA is done in stages, as you may need to increase your pH, to keep it from dropping below 7.0. It can take several adjustments, to bring high alkalinity levels down.

Hardness: The amount of calcium that is dissolved in the water. When calcium hardness levels are too low, you have soft water, and can see pitting and corrosion of plaster, grout and even vinyl. Soft water also foams more easily.

High levels of calcium hardness means that you have hard water, which can come out of solution, mix with dirt, and stain your pool surfaces, depositing as scale or crystals. Very high levels will even deposit in the heater or plumbing, like plaque lining arteries.

To avoid soft corrosive water and hard scaling water, test and adjust to the ideal range of 200 to 400 ppm. To raise calcium hardness, add calcium chloride, aka calcium increaser. For pools in hard water areas, that may see 700 ppm out of the tap, there is no easy way to lower calcium levels, but you can tie them up in solution by using a Stain & Scale control product.

Total Dissolved Solids: TDS is the total of everything that has ever dissolved in your pool. It can build up in the water when evaporation occurs. In most cases, TDS is not a concern for water balance, but for some pools with “old” water, and especially indoor pools (no rain), TDS can begin to “choke” the water after many years without adding regular fresh water.

Without enough dilution, some pools may notice the corrosion of metals such as pipework and filters, and problems with sanitation and cloudy pool water. Control TDS by adding fresh water seasonally.

To reduce TDS in pool water where draining the pool is not an option, some areas of the country have mobile pool water recycling rigs, that will pump out the pool, filter it with reverse osmosis, and pump it back into your pool.

Cyanuric Acid: A chlorine stabilizer bonds with free chlorine in pool water. It protects from ultraviolet rays and reduces the loss of chlorine in the water. Cyanuric Acid (CYA) allows you to reduce the amount of chlorine that is needed to maintain minimum chlorine residual in outdoor swimming pools.

When CYA is low in an outdoor pool, it can be difficult to maintain a chlorine level on a sunny day with many swimmers, and chlorine levels can drop dangerously low. When CYA levels are too high, over 50 ppm, problems can occur in maintaining chlorine levels sufficient to kill bacteria and algae.

Keep your CYA levels in the range of 25-50 ppm, by adding liquid or granular stabilizer to the pool. If levels exceed 50 ppm, lower by diluting the pool, or replacing 20% of the water.

TESTING THE WATERS

Test Strips, Test Kits or Digital Testers? If you want high accuracy, choose a Taylor or LaMotte test kit. Test strips from AquaChek or Insta-Test offer speed and convenience.

Digital pool testers offer the best of both, highly accurate and quick testing, with an exact digital measurement displayed.

test-kit-comparison-chart

~ Being in charge of a pool comes with many benefits and responsibilities. You stand between your swimming pool and your swimmer’s health! Make sure swimmers leave the pool as healthy as they came. Test your levels frequently, at least 3x per week, and make chlorine and pH checks daily.

104 thoughts on “Swimming Pool Water Balance Problems

  1. Christopher

    Thank you for your reply , thanks for explaining about the stain control . So based on what I placed in the water I should prevent stain on my plaster ?

    I have cynaric acid, would that help the calcium , rather than draining if imporued it in ?

    • Chris, if you keep adding a stain & scale control, on a regular basis, it will help control stains and scale. Do not add more cyanuric acid, if your level really is 150 ppm, I was suggesting that you drain the pool and refill with fresh water, in order to lower the level to 50 ppm or lower.

  2. Christopher

    Hello I have a 8000 gallon in ground pool , I have been testing myself with 2 seperate brand paper strips to make an educated decision . Both show my calcium at 500 based on my volume you said to try the stain metal control liquid in an earlier post . It said to add 13 oz , 2 days in a row I added and 2 days in a row it’s the same . I don’t want to damage the pool by keep adding .

    Ph is good , alkalinity is good chlorine is high but it comes down I’m in Texas so it’s hot.

    Stability is 150

    But the calcium is 500 , should I be worried?

    I noticed that I use to use shock once a week , all my chemistry was good except for chlorine which was high because if the shock .

    But I stopped using every week because it was too often for my use of the pool .

    What do you suggest please ?

    Thanks for all the good info you provided in other posts .

    • Hi Chris, The Stain & Scale control won’t lower the calcium level, but will keep the mineral (and metals) in solution, so they won’t come out to stain or scale on pool surfaces, or on your filter. Don’t worry about lowering the high calcium level, there is no chemical that does it well, plus 500 ppm is not crazy-high. For shocking your pool, if the pool looks good, and has low usage, you can shock just every 4-6 weeks, using 1 lb of pool shock. Now the stabilizer level at 150 ppm – that is going to be a problem. If you are sure that it is that high (150 ppm), I would drain half the pool and refill, twice. We like to see stabilizer (aka cyanuric acid) levels at 30-50 ppm.

  3. My pool was green when I arrived so I added a flocculant to kill the algae and then added ph+ as previously done.
    My chlorine level is high but the ph level doesn’t register as any colour at all. I know it should be between 7.2 and 7.6 which would show up as pale yellow, ut the water tested is clear. My son (a chemist) got me to test the tablets to make sure they were working and they were.
    I have added some ph+ to see if I can raise the level. The water has gone from cloudy green to cloudy blue
    I have also done a backwash a few days after adding the flocculant and surprisingly the water was pretty clear, it green
    What should I be doing to get the ph level right?

    • Hi Freya, flocculents typically settle the particulate matter to the pool floor, so you may need to fill the pool up high with water, to allow you to vacuum slowly to waste. If the pH test does not register a color at all, it may be because the chlorine level is very high, and ‘bleaching’ out the pH sample. What you could do is wait for the chlorine level to fall, which should not take long. Another possibility is that the pH reagent (tablets?) are bad and giving false results.

  4. Free chlorine is 8 ppm and alkalinity 75. Salt generator . 16000 gallon marcite pool. It is green and cloudy water. Told to add 5 lbs of alkalinity, but still same after 48 hrs. This is the second time this has occurred within the past 6 weeks. Never a problem before. Any suggestions?

    • Hi Karen, look at your pool filter. Clear water is partially about good water chemistry, but also a result of good water filtration. You may not be running the filter long enough each day, or the filter media my be worn out and letting small particles pass thru, or there may be deposits of oil or scale in the filter that reduce filtering. Or a valve problem (multiport) could be letting water bypass the filter, or the filter could be too small for the pool – fine when water is clear, but struggling to clear cloudy water…

  5. Rosemary wheeler

    Hi, My pool is around 8000 gallons and i have no idea what chemicals i should be adding to my pool and how much, can you help?

    • HI Rosemary, you’ll need two types of chlorine – 3″ tablets for everyday chlorination (24/7), and granular chlorine for shock treatment every few weeks, to kill anything the tablets missed, or for dealing with other problems like A-B-C, algae, bacteria, chloramines (and cloudy water). Some people use a weekly dose of Clarifier to help a small, struggling filter, or use a weekly dose of algaecide, if your pool is prone to algae. Now for water balance, you will need pH adjustment chemicals, either pH increaser, or pH decreaser, usually pools go one way or the other. Not needed so often, but on an annual basis, you may need to boost alkalinity or calcium hardness or cyanuric acid (stabilizer). And of course you need a good test kit or test strips. An 8000 gallon pool has the same chemical requirements as an 80000 gallon pool, just less of it.

  6. Hello, I have above ground 15×48 3,3000 gallon. I used 1 intheswim 3″ tablet on the floater. I live in Vegas so it’s hot here. My hardness is always 500 and I can’t balance my water, ph 8.4 and alkalinity 180 and stabilizer 0. I added 1 cup of stabilizer since it says 1 q for every 10000gal. Mine is only 3,300gal..added 6 oz pH decreser. Nothing is change. I add chemicals 1 day at a time as I am not sure if how those will react if the chemicals are added all at once. What to do?

    • For the stabilizer, it is 1 lb per 10000 gallons, to raise the level by 10 ppm. You want to be around 30 ppm minimum in sunny Las Vegas, so total would be about 1 lb., for your 3300 gal pool. Don’t worry about the hardness level, nothing can be done. But the pH, that is a problem being so high, and its your very high alkalinity that makes the pH very resistant to change. So… you will have to hit the pH hard with acid, probably every day for a week, to get that pH down. 6 oz of pH decreaser did nothing? Try 12 oz this time, and check pH after 2-3 hours. If no change, add another 12 oz and test again in a few hours. Keep at it like this until you get pH into the 7.2-7.5 range. Chlorine is more potent at this pH, but at 8.4, it is very lazy and ineffective, which can cause algae and bacteria to grow. Got to get that pH in line, very important! Thanks for asking…

  7. Dickson Murage

    Have pool added water and fixed new old solar water heater system checked chlorine levels it was low added chlorine and water turned dark brown.choline levels are ok but oh cant show even after adding solution 3 20drops no improvement of colour in the colour code kindly advice

    • Hi, so the water turned brown when chlorine was added? That would sound like a metal problem, possibly iron in the water. I would recommend using a sequestering agent like Stain Away, or Metal Free, or any liquid Stain & Scale chemical, to bind up the metals and minerals in solution, and prevent them from precipitating during water chemistry changes, like adding chlorine. Also be sure that the water is balanced with correct pH, alkalinity and hardness measurements. For the DPD water test, when adding reagent #3, if the test sample gets darker, that indicates the presence of chloramines or combined chlorine. If the color stays the same after adding 5-drops of reagent #3, then Free Chlorine = Total Chlorine, which means that no chloramines are present, or Combined Chlorine = -0-. Thanks for the question Dickson!

  8. pam carnes

    I have a 25 ft 5ft deep round pool. The test strip reads 0 chlorine, 0 PH and 0 alkalinity. After shocking still no chlorine., Tried 4 different kinds of test strips and they all read the same (thinking the first couple of bottles were bad) Any suggstions???

    • Hi Pam, I am still suspect of the readings because it’s not really possible to have a zero pH level and zero alkalinity (well, possible, but your pool would then be a big Vat of Acid). You may pick up a small liquid drop test kit – the ‘Duo Test Kit’ which checks only for pH and Chlorine, they are usually just $5 to $10, and see what results you get (test strips are inaccurate, and in your case, troublesome). Then, I would try shocking the *&^$% out of it – using 4 or 5 lbs of shock, after making sure the pH is below 7.6, so chlorine is most potent. (my theory being that some compound is consuming the chlorine, but – it could just be the test strips not showing chlorine, that IS in the water…)

  9. Hi we bought our first above ground pool and it’s fairly small it’s an index above ground 10′ round pool and is 2.5′ deep. It is only a 1,185 gallon pool and my PH is really high at or above 8.4, alkalinity is very very high at or above 240, and stability is at or above 300……. I’ve added to recommended uses of PH decreased in the pool but it’s still reading high and not lowering. Chemicals make me nervous and I’m not sure what to do! Any help or advise would be very much appreciated!!!

    • Hi Jenn, an alternate solution would be to drain most of the pool water and refill from the hose, which is what I would recommend if your Cyanuric Acid level (Stabilizer) is really near 300 ppm, and Alkalinity is truly at 240 ppm.

  10. Robert butt

    Hi I have a 20,000 gal above ground pool. The water is clear and looks beautiful. But all my readings are 0. 0 ph 0 alkalinity the chlorine jumps to low when I shock it. Put 5lb of ph increaser and 5lb of baking soda now results.

    • Hi Robert, you must have a faulty test kit or strip – because it would be rare to have 0.0 pH and alkalinity – that would mean basically a pool of acid. Can’t be that low! The best pool tet kit out there is the Taylor K2005, IMHO, or the Taylor Troubleshooter, is the best kit for $20.

  11. Jennifer Ruyle

    Hi we just currently got a pool above ground its 18ft by 48inch pool. We currently having issues with the alkality its about 200 ppm and the ph is about normal 7.6. chlorine levels are average range and total hardness is about 250 normal range.Been adding sodium bulsifate about 11oz to it every 6 hours to drop alkalinity been doing this for 3 days now. Its changed some but not a whole lot what else can i do. Iam getting very frustrated at this point please i need help.

    • Hi, just keep at it Jennifer, add enough to drop the pH to about 7.2, a larger amount, say a few lbs then wait a few days. If you can’t get it down lower than 150 ppm, you could operate at that level without much problem, in most cases.

  12. I have a 24,000 gallon inground vinyl pool with low pH or & low alkalinity and a metallic taste in the water chlorine levels were low I added shock but what should I use to bring the pH and alkalinity levels up and get rid of the metallic taste in the water . We have well water and it’s very hard water

    • Hi Kim, start with alkalinity, using Alkalinity Increaser to raise it, you’ll need approx 1 lb per 10000 gals, per 10 ppm, to reach 90-100 ppm. After 8-12 hours, check the pH level, and if it is still low, add pH increaser to bring to the range of 7.2 – 7.6. As for the metallic taste, that’s a new one – I’ve never had that request but since you mention that you are on well water, there could be high levels of minerals and metals. Using a sequestering agent such as Stain Away, Metal Free or Jacks Magic Blue Stuff, will lock the minerals/metals up in solution, to prevent staining and water quality issues, and perhaps water taste issues as well.

  13. Hi, I have the pool test kit drops and the test strips. My test kit is contasntly read my pool chlorine at high levels – in the 5-10 area but my test strips are reading at a 3. I’m not really sure what to do or which is right at this point

    • test kits are considered more accurate than strips, but both are subject to interpretation. You could take a sample to a local pool store for testing, to see what it really is.

  14. Bobbi Jo Rainey

    I have an 18ft 48in above ground Coleman vista series pool. This is the 1st time I’ve ever had a pool n I’m trying to get it straight with the chlorine level n everything but I’m having trouble. On Sunday I put 2 3in chlorine tabs in a floater n Sunday, Monday, n Tuesday I got a zero reading on chlorine and bromine level n on Monday and Tuesday my ph was good reading between 7.2 n 7.5 then Wednesday still showed zero on chlorine and ph dropped to 6.8. I noticed algae around bottom sides so Tuesday evening I put a bag of shock in it. My pool is 7,646 gallons n the shock was for 10,000 gallons. I wasn’t thinking about that when I did it but I realize now it was too much. So now my chlorine n bromine is 5 n 10 n ph 6.8. I’m getting frustrated now cuz I just don’t know what to do to get it all correct. Help please

    • Hi Bobbi, youre doing good – thinking about the right things. Keep enough tablets in the floater to give you a consistent and constant chlorine reading of 1 to 2 ppm (don’t worry about bromine). Keep the pH at the good level. Looks like it is now low, so you would add a pH increaser (soda ash) to raise pH somewhat. Just need a pound or two, see label instructions. No problem with using a bit too much shock, It’s best to use the entire bag, for safety anyway. Just keep the chlorine and pH managed – you’ll get it sorted out! Enjoy the summer, let me know if you need my help! Davy

  15. Hi,
    Our commercial indoor swimming pool has never had any problem in 17 years. In the last 8 weeks the pH has risen to 6.7. The alkalinity on first test is 400 but second test is 100??? Why??? The calcium is 200. We are using 2 types of testing palinstest kit and multiple tablets to establish water balance. We have added 1.5lbs of sodium carbonate per 20,000 gallons pool water to lower pH but this only adjust pH temporarily. The co2 gauge on cylinder has not changed. What can you suggest we do? Is it an alkalinity problem that is making pH resistant to change? Thanks!

    • Hi Marco, the discrepancy in alkalinity tests could be a variety of testing errors or expired reagents. Repeat until you can confirm the test twice, with the same results, or buy new test tablets. High alkalinity will make pH resistant to change, or make the pH change only temporarily, but 100 ppm is not high (altho 400 ppm is very high). If your pH level is 6.7 – that is not high either, but actually low. 7.2-7.4 is a range I like to use in most cases. Sodium Carbonate is used to raise pH (not lower pH), also known as Soda Ash, or pH increaser. Sodium Bisulfate or dry acid, is used to lower pH. you mention a CO2 gauge – adding CO2 to the water will raise pH levels when added to pool water.

  16. Tom Wasson

    I, my in ground pool chlorine is really high and everything else is low as it can get. What can I do to fix it?

    • Hi Tom, the high chlorine will come down on its own, just stop adding more, of course. For low pH and Alkalinity, use soda ash or pH increaser, or alkalinity increaser. For low calcium hardness, use calcium chloride, aka calcium hardness increaser. For low stabilizer levels, add cyanuric acid. For the correct amounts, consult the label, or use poolcalculator.com.

  17. Steve Cooper

    Hi. I have a fibreglass pool that has suddenly developed grey stains below the water line. Test strips reveal that the chlorine, pH and total alkalinity levels are OK so I took a water sample into a local (in France) pool equipment supplier. I’m not a fluent French speaker but I understood enough for them to say that the water was dead and that the only solution was to completely drain the pool, clean the sides and refill. I’m reluctant to do this so is there anything else I could try? Thanks

    • Hi Steve, you could try to use a sequestering agent, a Stain & Scale chemical, if it is metal/mineral, it may remove some of the staining. If it is a bathtub ring stain, you can lower the water just below that area and scrub gently with small amounts of Soft Scrub or other chlorinated abrasive cleanser, or pour a weak acid solution over the wall from a flower watering can, scrub, then rinse.

  18. I have a 22′ x 54″ above ground metal frame pool. 10,669 gallons at 90% capacity. My ph is 8.2+ (my liquid test kit does not go above 8.2, and it is bright pink) i have already added 20oz of phdown yesterday. Today it still reads 8.2+. My cyanuric acid test shows less then 30ppm. What am i doing wrong?

    • Hi Megan, if your pH does not seem to budge, that could be a result of high total alkalinity, over 120 ppm, which makes pH resistant to change. Use pH decreaser also to lower alkalinity, and once it comes down enough, the pH will also come down. Just keep adding it in 1-2 lb increments over a few days, until Alkalinity comes down below 100 ppm.

  19. Curtis Warrensford

    I have good chlorine level.Low PH. Low Total Alkalinity.Low Cyanuric Acid. What should I do.

    • Hi Curtis, start with the alkalinity. If below 75 ppm, add some alkalinity increaser, to raise it up to around 90 ppm. This will also raise your pH a bit, but if still below 7.2, add a pH increaser to raise the pH. Low cyanuric, below 20 ppm, can allow the sun to burn-off much of the chlorine. Not needed for indoor pools, or all-day shaded pools. Chlorine tablets have a bit of cyanuric acid ()aka stabilizer) pressed into each tablet, which will raise the level naturally over time, depending on how much rain and backwashing you do, which dilutes the level. Add Stabilizer to the pool if needed, to raise 10 ppm, add about 1 lb per 10000 gallons.

  20. Michiel Diening

    I have a brand new underground / vinyl lined pool in Greece that has approx 155m3 of water volume.

    I have tried to balance my consistently high (= +8.2) pH values with over 20kgs of pH Down over the last 10 days…. But… it keeps returning to the high 8.2+ readings.

    Please advise me on what I can do the balance my pool water.

    • Hi there – check the Total Alkalinity level, it may be too high, which buffers the pH to keep it overly stable. 20 Kgs (44 lbs!?!) that’s a lot of pH down. Lowering alkalinity to below 100 ppm should be the trick, which is done with the same chemical pH down, but more added all at once – perhaps a double or triple dose, which will pummel the pH, possibly pushing it below 7.0 – at which point you may need to raise the pH level, and then lower alkalinity again, continuing to adjust both until they come into range. Also, be sure that your test reagents are in good shape and not giving you false readings, which can happen if they are expired. Or, if chlorine levels are very high – this can produce a false high pH (purple color readings for pH test).

  21. Our gunite poo, was resurfaced last summer. We noticed sandy deposits on the bottom of the pool. We had that material tested and we were told that it was actually the gunite and not sand. We have been told that this is happening because out chemicals are off and then someone told us it was because the gunite was not allowed to cure properly before the water and chemicals were added. Need some advice

    • Casey, that all sounds like bad advice, perhaps hoping to sell you some chemicals – most likely it is wind blown dirt or sand from nearby construction, or grit from a concrete pool deck, or could be filter sand, if you have a sand filter. No worries. The gunite is underneath the plaster, and it has cured years and years ago. Not a gunite problem – how do you even test to determine the difference between sand and gunite? Was this a pool store that told you that? Geez…

  22. Hi, first pool…above ground 15’x48″. Water is murky and there was a slight scum on top today.

    Chlorine has always read below 1.0
    PH has always read 8.0-8.4 range

    I have a chlorine tablet floating around. I also added a 1/2 pound of pool shock yesterday morning, the other 1/2 pound just this morning. I was nervous about adding the whole pound (1 bag) because my pool is only about 5,000 gallons of water and it said use a whole bag for 13,000 gallons.

    I know my chlorine needs to raise quite a bit and PH needs to lower quite a bit. Do I add more shock? I’m assuming the shock will help the chlorine, but I’m not sure about the PH. I don’t want to add too many things as I know that can also mess up a pool quickly. I think I read in a comment about a PH decreaser. Could I add that while shocking?

    Thanks!!

    • Hi Lori, first thing is to get the pH level down to 7.2-7.4, where chlorine will be more than twice as effective and potent, compared to 8.2. Also, algae prefers a higher pH level. Use pH decreaser (aka ph down, pH reducer, pH minus, dry acid). Add 21 oz. for your 5000 gallon pool. Recheck pH a few hours later, and when it is near 7.2, shock it with an entire bag of shock. The bag dose is for a clean and clear pool, but for signs of visible algae or cloudy water, a double or triple shock is not unusual.

  23. HI. My pool is cloudy and milky looking. The water is perfectly balanced, but i’m not reading any chlorine. We don’t have any metals either We treated for a chlorine lock but nothing is showing up still.we have also tried drop out but it still stays cloudy. we have a vinyl liner and a sand filer. the sand is brand new and only 0ne year old

    • Hi Caitlynn, high cyanuric acid levels, over 100 ppm can give trouble obtaining a chlorine reading. If so, dilution is the solution, or using BioActive cyanuric acid reducer. Sand filters can benefit from using a Clarifier, or attaching a Slime Bag to a pool return. Aluminum Sulfate, aka Alum is the real flocculent, but requires a slow vacuuming to waste the following day. Keep running the filter non-stop too, if you are not already doing so…

  24. Danielle Anderson

    Ok Heres my predicament I have small above ground pool for the kidos 1,018 gallons and just the other day after some heavy use it clouded up. I use two different types of test strips and just shocked the hell out of the water tonight with a product that also kills algae. these are the results from my newly bought test strips
    Total Hardness 100 low
    Total Chlorine High side of Ideal
    Free Chlorine IDEAL
    PH 7.2
    TOTAL Alkalinity 120
    Stabilizers 30
    So I can’t for the life of me understand why The pool is cloudy and what I should try next to fix this issue any help will be greatly appreciated.

    • Hi Danielle, it could be the filter – not running long enough each day, or needing cleaning, or needing a new cartridge element. Run the filter non-stop for now, and perhaps increase the daily run time to compensate for warm weather and heavy pool use. On the chemical side, when total chlorine is higher than free chlorine, the difference is combined chlorine, which calls for a shock treatment, to remove. Also the Calcium Hardness level is best around 200 ppm, adding 1 lb. of calcium chloride will bring it up. Using some Clarifier can also help improve filtration. (I see your other comment – good that you replaced the cartridge – and keeping the pool clean reduces chlorine demand, as debris uses up some of your sanitizer)

  25. Salt water pool. Had it finally cleared up, left too long without adding more chlorine. now its green and cloudy….

    ph is around 7.4
    alkalinity around 200 (maybe higher)
    stabilizer around 30
    Harness is high i believe, based on test strips but do not have reading
    FC 2ish

    added a bunch of chlorine and it doest seem to be getting any better!

    Thinking hardness might be too high? Would this cause the green and cloudy?

    Appreciate any help!

    • Hi Chris, high hardness and alkalinity can contribute to cloudy water, and the particles can get in the way of chlorine trying to do it’s job, and kill algae. But not much you can do about it, except to add more shock chlorine – enough to turn the water from green cloudy to blue cloudy. Then after 24 hours, add a Clarifier, or for small filters that struggle, add Dicalite to sand/cartridge filters as a filter aid, or use the Slime Bag on the pool return. Also, keep filtering the pool non-stop, 24/7 (it won’t blow up!), and wait to backwash until pressure is around 10 psi higher, or flow rate is noticeably diminished. If it still won’t clear-up within a week, consider changing the filter cartridge or filter sand.

      • Thanks! Is it ok to shock two days in a row ?

        its 35,000 gallons I put in shock for about 40,000. This am it is lighter but not the normal blueish that it normally turns

        Thinking about adding new sand to the filter, however i have not done this before

        What sucks is we have a cookout sunday!

        Awesome resource thank you so much !

        • Hi Chris, yes ok to shock again, until it turns a blue-grey color. Changing sand is not too hard, we’ve blogged about it a few times. You may need a clarifier to help clear the water, even with new sand. Keep running the filter! And check that pH is in a good range, not too high.

  26. Please help! Can’t get my pool water balanced at all. Rough winter with a pool cover failure, initially had lots of debris but got it all out. Had the water clear after it being dark green.
    It went cloudy again and now is green and cloudy.
    Current readings:
    Hardness 250
    Total Chlorine 1
    Free Chlorine 1
    pH 6.8 (have gone up and down for the last week)
    Alkalinity 180
    Stabilizer 100

    Not sure if I should add muriatic acid to lower Alk knowing it will also lower pH or should I raise pH then add muriatic acid.
    Thank you

    • Hi Kimberly, the best solution is to replace 1/2 to 2/3 of the pool water, mainly to lower the cyanuric acid (stabilizer) level, but also a good opportunity to get rid of the contaminants that are keeping the pool green, and making a full recovery difficult. Should also give you better pH/alkalinity readings (you can test the fill water to know what you’ll get). If your filter system won’t lower the water level that much, rent/borrow a submersible pump to do it overnight. Let me know if any other questions.

      • Thank you for responding. I had actually drained it about 1/3 or more last month. I also accidentally drained and replaced a significant amount last week. I started with a high alkalinity of 240 prior to the first draining and replacing. It’s held steady at 180 since.
        It’s a 24’ above ground roughly 14k Gallons. Would like to avoid draining again.

        • OK no draining – my concern is not really with the alk/pH, although that’s a bit whacky right now, but with the stabilizer level of 100 ppm, which makes chlorine very lazy, and requires chlorine levels of 5-7 ppm normally (everyday) and shock chlorine levels of 20-25 ppm for light algae removal, to compensate for the suppressive effect of the cyanuric acid. There is a product called Bio-Active that is a stabilizer reducer, as an alternative to draining and refilling.

          You can keep the high cyanuric acid level, but will need to run high levels of chlorine to ensure sanitation (Bacteria removal), and for this current bout of algae, a large dose of shock will be needed to reach a breakpoint threshold. For 14K gallons, use 5 lbs of pool shock, and you should see it blue up within 15 minutes, if not add another pound or two. Run the filter constantly until the water clears, cleaning only as needed to keep flow rates normal, and use enough tablets to maintain at least 5 ppm of chlorine this summer.

          For the alk/pH problem of low pH 6.8 and high alkalinity 180 – i would start with raising pH to 7.8, then add enough acid to drop pH to 7.2, then raise pH again, add acid again – keep doing it for about a week, until the alkalinity comes down to 140 ppm and pH stable at 7.2-7.4. But wait until you get the algae under control first, then tackle that problem… 🙂

          • Thank you so far. Added shock as suggested, took a bit but did turn blue but very cloudy.
            Ended up getting a water analysis done which showed 3 issues:
            Low Hardness @ 120
            High Alkalinity @ 140
            High phosphates @ 2500

            I have the alkalinity @ 120 now. Ph is
            low which I can tackle. Any suggestion besides The 23.9 lbs of hardness up and the almost 6 qts of phosfree the pool store suggests? I only ask because it’s not cheap and they obviously want me to spend money there.

          • Hi Kimberly, that sounds solid – the phosphates are the main problem, 2500 is a very high level. Follow the PhosFree label instructions closely, and after treatment have the phosphates tested again, or we have phosphate test strips, if you want to do it yourself. Get the phosphates down to 200-300 ppm and you should be fine.

  27. Julie I Davis

    I’m so lost. I keep trying to no avail.
    Hardness ok
    Total and Free chlorine very low
    PH high
    Alkalinity very high
    Stabilizer very low

    I just need steps to get this under control. My pool is green and cloudy now. I have added chlorine multiple times it goes cloudy blue and within a day it’s back to green. Please help!!

    • Hi Julie, the high pH is likely making your chlorine so lazy, that it can’t kill all the algae. You also have high alkalinity which makes it difficult to lower the pH and keep it lower…

      So, the first thing is to lower the alkalinity and pH – which the algae won’t like, they prefer high pH water 🙂 If you are using pH decreaser, add enough to get alkalinity down to 120 ppm. Doing so may lower your pH down too low, and if below 7.2, add pH increaser then, to bring pH up a bit – which will also raise alkalinity again, by a small amount, so sometimes a little back and forth in the manner, is needed, when both pH and Alk are very high.

      Once pH can be stabilized at 7.2-7.4, shock the pool with 1-3 lbs of shock per 10K gallons, depending on the severity of algae (light, medium, heavy)… And be sure that filtration and circulation are optimized and working overtime, which is important to finally restore the clear water.

  28. Hi,
    I have struggled the last month balancing my 16×32 inground.It is cloudy and a bit green.
    I bought a Aquatest Trutest but doesn’t give me consistent readings. At this point my ph and alkalinity are balanced but my chlorine is low. I shocked with .454 kg yesterday should I continue to shock?

    • Hi Christy, half a kilo is not much shock, unless your pool is very small, under 10,000 gallons. Add 1 kilo per 10,000 gallons, and then you will see blue water.

  29. Glenn & Shirley Bates

    We cant achive a free chlorine reading on our test strips. We use Bio Guard products. We have added many pounds of shock and tablets in the automatic feeder. The problem started last year and it is worse this year. The pool is 14 X 28 inground with a Hayward DE filter. The pool liner is 9 years old. Could that be lockink or eating all this chlorine?

    • Assuming that the test strips are not giving false readings, and assuming a good pH level in the range of 7.2-7.5, there is something in the water that is consuming chlorine. Could be nitrates or phosphates, which can be removed with Phos-Free or other phosphate removers. Also possible is that a breakpoint threshold needs to be reached to remove chlorine byproducts – in the area of 30 ppm, which is usually achieved with a triple shock, or 3 lbs of shock per 10,000 gallons, plus a little extra, just to be sure 😉

  30. I have an older 16’x36’ in ground plaster pool with crazy Chem levels that I can’t get under control. I’ve spent several hundred dollars on chemicals this last month and replaced my filter cartridges and nothing seems to help!!! My total Hardness is >500 free and total chorine remain at zero within 24 hours after a ton of chorine and shock are added, Ph remains low after pounds of Ph increase has been added, total Alkalinity remains extremely high and won’t budge, and stabilizer remains low several days after adding over 7 pounds of stabilizer!!! I’ve added metal catchers to both baskets for over a month now and run the pump consistently for a minimum of 8 hours a day! I have solar heating panels on my roof and have gotten the water temp comfortable and would hate to delay opening my pool further due to temp by draining and refilling my pool….. Are there any other options or is my pool water just simply too old to repair????

    • Davy Merino

      Hi Danielle, at this point – just focus on the chlorine level, don’t worry about the other chemicals. Something is consuming the chlorine shock added, and you need to reach a breakpoint threshold of oxidation, where the contaminants are finally removed. Assuming your pool is 20000 gallons (?) I would recommend 10 lbs (!) of 65% cal hypo shock, added in the evening, with the pump running all night (or as late as you are comfortable leaving it run). The next morning, if chlorine level is zero… shock it again – this time with 12 lbs of shock. Or just start with 12 lbs – your choice – but you will know it worked when you can test a good chlorine level the next day (should be high). Also, be sure that your test strips or reagents are fresh, otherwise you could get false test results.

  31. Christy Schoenbein

    Ok our in ground pool (around 25,000 gallons”) is so clear and blue put yet total chlorine is low, free chlorine is low, cyanuric acid is low and ph is low…total hardness is fine and total alkalinity is fine. I don’t understand how it can be so crystal clear and blue but everything is low!!! Please help!!!

    • Davy Merino

      Hi Christy, the low pH and low water temperatures are likely keeping it good – plus you may have a big, effective pool filter…? For clear water, free chlorine level is best in the 1.5-3.0 ppm range, unless you have a mineral purifier, like Nature2, then you can run it at half that much.

  32. We just filled our 30ft above ground pool. I am trying to get it all level any tips would be helpful. It says my ph is low 6.8, total alkalinity 180, and stabilizer 0. My chlorine and free chlorine is good. I have added some stabilizer but it hasn’t changed it any.

    • Davy Merino

      Hi Amanda, stabilizer sometimes takes a few days to register, test again it may be reading now. I like to see 30-50 ppm of cyanuric acid (Stabilizer). For the ph/alkalinity – that is a bit of a problem as you may know. You have very low ph and very high alkalinity. But to lower alkalinity we use … pH decreaser, which will depress your pH even lower. First you would raise pH to 7.6-7.8, then add a pH reducer to lower the alkalinity, then raise the pH again, and then you will likely need to lower alkalinity again. Such a high alkalinity makes it hard to adjust the pH, so it can be a bit of a back and forth battle. Ideally, your pH should be 7.2-7.6, with alkalinity of 80-120 ppm. It’s ok if your alkalinity only comes down to 130-140 ppm, as long as you can get your pH to remain stable in the 7.2-7.6 range. Low pH of below 7.0 can harm your pool liner, over time, as it is a bit acidic.

  33. Hi, I have a small pool above ground. It is approximately 1700 gallons. It stayed clear all summer and through the winter using just chlorine tabs. Its just getting warmer here in GA and all of a sudden it turned green. I used bagged 7 in one shock that said it was safe for this type of pool. It cleared up the green but I tested the water and it says there is no chlorine, the PH is low and the alkaline is low. Any idea what I should do for this? Thank you.

    • Davy Merino

      Hi, assuming you can trust your test strips or reagents (fresh?), then it just means that the algae and other gunk consumed all of the chlorine. The rule of thumb is – 12 hours after shocking, if the chlorine level is zero… shock again, a bit heavier this time. When shocking a pool, a low pH is preferable as the chlorine is much more active. However, low pH and alkalinity over long periods of time can damage your pool liner. So, work on raising ph into 7.2-7.6 range and alkalinity of 80-120 ppm. Use pH Increaser to raise pH and Alkalinity Increaser for raising… alkalinity 🙂

  34. Donnie Nguyen

    Hi Davy. Need help please
    Total hardness : very high (1000)
    Total chlorine : very high (10)
    Free chlorine : very high (10)
    pH : very low (6.2)
    Total alkalinity : very low (0)
    Stabilizer : low (0)

    Pool is running high the last 3-4 days after treating for about 12-16 hours a day. Pool is cloudy but blue. Could kind of see near the bottom though. Did use some pool clarifier and phos-free. Any help would be appreciated.

    • Davy Merino

      Hi there, ouch! OK… any possible way to drain and refill with better water? 🙂 If possible even to replace 1/4 of the water, that would be a good start, but if not I understand, and I would start on Alkalinity, adding Alkalinity Increaser (bicarb) to the pool, at a rate of 19 oz, (1 lb 3 oz) per 10,0000 gallons, to raise 10 ppm. You will need a Lot! And also need a reliable test kit with Titration TA test, like the K2005 test kit. Add the Bicarb in 3 or 4 smaller doses, not all at once, to avoid sending the pH level thru the roof, which could cause more cloudiness and scaling. Brush the deep end for a few minutes, then turn on the pump again. Adding so much bicarb will raise your pH, so after a few hours of circulation, re-test Alk and pH, lower pH if above 7.8, using pH Decreaser (acid) and then add more bicarb, until you get 80ppm TA and a pH of 7.2-7.6. It can take a few days sometimes, try to remain patient!

      By this time, the chlorine level should have dropped to within normal range. Add a bit of cyanuric acid, 2 lbs per 10000 gals, to establish a base of 20 ppm, important to protect chlorine from the sun during the day time. The hardness is very high at 1000, which can cause bouts of cloudy water, scaling stains on surfaces, and other water management problems. Dilution is the Solution, again if possible to add softer water, replacing some of the water. Also avoiding cal hypo pool shock, which contains calcium. But most importantly, using a good sequestering agent, every 2 weeks like clockwork, to keep scale minerals locked in solution, where they can’t come out to play.

      • Donnie Nguyen

        Hey Davy. Thanks for the fast reply. Haven’t gotten a chance to buy alkalinity increaser, pH decreaser, cyanuric acid, sequestering agent, and the test kit yet. Gonna put in an order soon since spring is here and summer is around the corner. But I want to update you a bit. Left the pump running for a day or so and now the water is pretty cleared. But my readings still isn’t where it needs to be. Current readings are:
        Total hardness: 250 (ideal)
        Total chlorine: 3 (ideal)
        Free chlorine: 3 (ideal)
        pH: 6.2 (very low)
        Total alkalinity: 40 (low low)
        Stabilizer: 0 (low)

        Forgot to mention the pool size in my first post. It’s 19500 gal. Should I still follow your original guide or do I need to change it up now? Thank you for all your help

        • Davy Merino

          Wait a minute – how does your calcium hardness go from 1000 to 250 in just a few days, lol…! Must be a testing error, or you’ve got a million dollar solution to high calcium hardness levels! Actually calcium hardness can be reduced by precipitation and filtration, but not by usually that much (750 ppm). Anyway I digress, yes the original advice does not apply so much now. I would add 15 lbs of soda ash (pH increaser), all at once, brush the pool, then filter for a few hours and retest ph and alkalinity. You may be able to add alkalinity just by raising the pH. If the alkalinity remains low, add 2.2 lbs of Alkalinity Increaser (sodium bicarb) for each 10 ppm needed, to reach 80 ppm. For stabilizer, add 5 lbs of cyanuric acid to raise it to about 25 ppm (for your 20K pool size)

  35. Sarah Rich

    14,000 24 ft above ground pool, pump constantly running and filter cleaned 3 times this week,vacuumed, added chlorine and tablet, went from very low to very high, still greenish. Added shock and 1 gallon of muratic acid. Reads high ph, High alkaline,High chlorine and everything else normal range. I am baffled.

    • Davy Merino

      Hi Sarah, when chlorine levels are very high, it can affect the pH test, making the pH appear to be very, very high. Since you added a gallon of acid (?), it should be very, very low actually. If you have a full test kit, like a Taylor with 3 bottles for testing alkalinity, the first bottle is a chlorine neutralizer- you can add a few drops to your water sample before testing pH, to remove the chlorine interference, as it’s called. In most cases, if the pool is still greenish, you may need more chlorine, if not changing to blue rather quickly. Good chance that your filter is struggling. Might need a new filter or filter sand, either now, or just after clean-up.

  36. Hi Davy,
    My pool 20,000 gallons water was too old, I DRAINED ALL WATER and REFILLED with fresh water.Please help me how to start to add chemicals to bring water balanced….
    Thanks,

    Ha

    • Davy Merino

      Hi Ha, Start with Alkalinity and pH levels, testing and adjusting to 7.4 for pH and 100 for alkalinity, then test calcium hardness and cyanuric acid, and adjust calcium to 180 ppm and cyanuric to 20-50 ppm. Start adding chlorine tablets immediately, and after balancing water you can shock the pool if it looks hazy or dull.

  37. Abbey Sanders

    Hey there. The pH in our pool has a high reading. Just wondering how to lower the pH level. Our pool is blue but cloudy. We cannot see the bottom. Any insight would be great. Thank you

    • Hi Abbey, pH is lowered by using an acid, such as pH decreaser (sodium bisulfate) or the liquid muriatic acid. A nice test kit like the Taylor K2005 can do an “Acid Demand” test, to tell you exactly how much chemical to add, or you can use poolcalculator.com to compute the amount needed, or consult the pH decreaser label. Just add directly to the water, and test the pH again after a few hours of running the pump. If your pH is erratic, moving all over the place, the Total Alkalinity may be too low. If your pH is difficult to change, you lower it but it pops right back up again, your Total Alkalinity may be too high – TA should be 80-120 ppm – so if you have to struggle with your pH level, check the alkalinity. A pH level of 7.2-7.6 is best, to help chlorine work most effectively, and to control scale and cloudy water. When pH rises, calcium likes to come out of solution, and cloud the water, or deposit itself as scale on surfaces…

  38. I can’t get the levels balanced in my pool what else can I do, it’s showing 0 chlorine 0 free chlorine 6.8 ph total was ok now is reading high stabilizer 0 we have tried everything and nothing is working

    • First thing is to add some granular chlorine, or liquid bleach for smaller pools, to raise the chlorine quickly. then get to work on the pH, adding enough pH increaser to raise the pH out of the acidic range, and slightly alkaline, in the range of 7.2-7.6. If you have trouble raising it and keeping it up, check the alkalinity, it may be too low or too high – should be 80-120 ppm. For the cyanuric, using trichlor tablets will add a little bit at a time, but on a freshly filled pool, adding flake cyanuric acid will raise it, 1 lb per 10000 gallons will raise it 10 ppm. Maintain cyanuric acid in the 20-50 ppm, so only 2 lbs is needed, per 10K gallons, to start. Then tablets will add more over the summer. Use enough tablets in a floater or feeder to maintain a constant and consistent 1-2 ppm of free chlorine in the water, verified by your testing. Add shock chlorine if you see algae, suspect bacteria, or have a discernable difference in total chlorine and free chlorine readings (which is combined chlorine or chloramines), or if you forget to add tablets and it drops to zero, or if the filter or pump system is not working. Speaking of – be sure to run your filter long enough each day, depending on it’s size and performance, it needs between 12-24 hours per day, to filter effectively, during summer.

  39. Hello my chlorine levels are to high free chlorine and total chlorine at 10 how can I lower them down

    • Hi Adrian, it will come now naturally, over the next few days. There is a chemical Sodium Thiosulfate that will remove chlorine, if you need to do it instantly. Running the pump and removing any pool covers will help speed up the natural process.

  40. My pool has been green for a week. I used green to blue x 2 and vacuumed my pool today and the water is finally looking clear. When I check the ph is orange (I used a liquid tester kit) I know it is off the chart but I don’t know if it means too high or too low. When I checked the chlorine it also is clear which is not on the chart. What do I do now??

    • Hi, If the pH is yellow-ish, it’s low, if it is violet-ish it’s high. Nicer test kits have acid demand and base demand tests, done with the ph sample, to know how much to pH chemical to add. If the chlorine test is clear, that means no chlorine usually. Add a few chlorine tablets to a floater or chlorinator, to maintain a constant and consistent 1-2 ppm of chlorine in the pool, at all times. To give it a boost, since chlorine is near zero, add a lb. of pool shock, to boost it quickly, it will take too long for tablets to dissolve, then water will go hazy, and green again. Keep the chlorine high and the pH low, for best results in killing algae.

  41. Joe Mancebo

    The test I have only tests pH and Chlorine, both seemed to be off the chart, pH being too low, and chlorine being too high. It’s a large outdoor pool and it’s clean and clear. Yet the water is green! I have about 10 tablets in the pool.

    Any ideas what I should try?

    • Davy Merino

      Hi Joe, clear and green can mean metal contamination, not algae. Treatment for such would be to use a sequestering agent like Safe-N-Cleanor Stain Away to keep metals and minerals locked up in solution. Follow label instructions for application, and maintenance doses, as it will deplete over time, usually in 2-3 weeks. Another good product is Culator, which traps metals in a packet or pouch.

  42. After testing my pool liquid test solutions and confirming with with test strips, I have to add one quart of acid almost every other day.

    Do you have any suggestion to help correct this pH problem? The pool is not recently filled.

    Today’s test results are:
    Total Hardness +-1,750
    pH=8.0
    Total Alkalinity = 175
    CYA = +-150

    Any knowledge you may be able to share would be appreciated,

    Bob

    • Davy Merino

      Bob, you need to drain the pool, those readings are off-the-chart high. The problem with your pH is caused by your high alkalinity, should be only 80-120 ppm. It’s buffering the pH too much, causing a strong resistance to change, so it’s not surprising that it’s hard to adjust. The total hardness coupled with the high pH problem can give you cloudy water, scaling and calcium deposits. the CYA at 150, makes your chlorine very sluggish and impotent, and the water is likely not as sanitary as you think, and it can lead to algae troubles. IF your readings are correct, I would strongly advise you to drain and refill at least half of the pool water. If that is not possible, use lots of acid to drop the Alkalinity back down, probably several gallons all at once, poured into the deep end, with the pump off for 20 mins, then turn pump back on. You can also try BioActive to reduce cyanuric acid down to 30 ppm, might need 3 treatments, at $50 a pop.

  43. Trish keating

    Hi I just bought a new 10ft pool and I finally got in the alkalinity to the exact amount in the pH to the exact amount but my free chlorine is way up… how can I bring that level down?

    • Davy Merino

      Hi Trish, it will come down naturally, usually within 3 days. We do sell chlorine neutralizer (Sodium Thiosulfate), but that’s mostly used in commercial settings where the pool or spa must be operational for the guests or users. Remove any covers on the pool for faster reduction in chlorine levels, and to protect the cover.

  44. total chlorine is low, free chlorine is low, ph is high, alkalinity is high, and stabilizer is low

    • Davy Merino

      Start by adding a bit of stabilizer (conditioner or cyanuric acid) to raise cya level up to at least 20 ppm, up to a maximum of 50 ppm. Next, drop your pH level to 7.2, which should lower the alkalinity as well. High alkalinity may resist the change, so you may need to lower pH several times, until both pH and alkalinity come into range (PH – 7.2-7.6 and Alkalinity of 80-120 ppm). Once those things have stabilized – then shock the pool, using 2 lbs of shock per 10000 gallons. Then you should be ok…?

  45. Deborah Bellizzi

    Hi all of my levels are low so I’m not sure if I should shock it or add each chemical on there own.

    • Hi Deborah, there is a preferred order to water balance and shocking:
      1. Alkalinity First – 80 – 100 ppm
      2. adjust pH to the low end of the scale, 7.2-7.4
      2. Calcium Hardness – 180-220 ppm
      4. Cyanuric acid – 20 -50 ppm
      5. Shock – 10-20 ppm

      Chemicals should always be added on their own, separately. For a pool guy, charging by the hour, that’s often hard to do, but for a homeowner I would try to give the water an hour or two between each of the 5 steps above, or for each chemical added. This gives it a chance to adjust on its own without a lot of other chemical reactions going on at the same time.

      Specifically for shocking a pool, a low pH 7.2-ish is best for the ‘shock reaction’. Add in the evening or when the sun is not directly shining on the pool.

  46. John Smith

    Hi,

    I have a pool that is constantly green no matter how much chlorine or shock I add. I do have a slow leak in the pool. Pool is 5000-6000Gallon, in-ground cement wall. I add about 175 gallons of water every day which I believe about 1/2 is due to evaporation and rest is leak. Pump is run 8hrs a day. My PH level is constantly low (6.8) and chlorine level is always low even when I have 4-5 3″ chlorine tablets in the chlorine basket! No one uses the pool. Below are the measurements:

    tap water:
    PH=8.0
    Total alkalinity = 100

    Pool water= PH= 6.8 (raised it to 7.1 after adding 5lb soda ash!
    Alkalinity= 60 when PH is 7.1

    – Why is my alkalinity always low?
    – I assume my chlorine level is always low because Alkalinity is low which results in green?

    PLEASE HELP!

    • I don’t think the low chlorine is related to pH or alkalinity. It does affect it’s potency, chlorine is much more active at a lower pH/alk, but does not affect the chlorine demand. Your pool either has a rather high chlorine demand, possibly from excessive debris, swimmers, animals or oils, possibly poor filtration. Could possibly be bad test kit reagents or bad test strips. And finally, it could be that the level of stabilizer in the water is so high (above 100 ppm), that ‘chlorine lock’ has occurred, making it hard to obtain a reading. It’s not the pH/alk, and it’s not the water loss – not really related to the no chlorine reading. Check your cyanuric acid level, if that is not the issue, and it’s not bad test strips, consider adding a Phosphate remover to the pool. If that doesn’t fix it, I would really shock the pool hard with granular chlorine, about 3-4 lbs, to see if it can break whatever is consuming the chlorine.

  47. My cyanuric acid is always high when everything else is good. Do I need to drain the pool?

    • Hi Sylvia; Cyanuric Acid (aka conditioner or stabilizer) rises slowly over time, from the use of stabilized chlorine tablets, or all at once from an overdose of flake cyanuric acid. The correct level is 30-50 ppm, although it can be higher, but once approaching 100 ppm, chlorine becomes very lazy, and at such point, it needs to be lowered, to keep your water sanitary. There are two ways to do this, drain a portion of the pool, and refill with fresh water. Simple math – if your cya level is 100 ppm, and you replace half the water, you should end up at 50 ppm. A new chemical was introduced in the last year, called Bio-Active, which can reduce up to 50 ppm of cyanuric acid, at a cost of $50 per treatment.

  48. My alkalinity is 100 but my ph is too low and does not even register on my test. Does this mean I have to drain my pool?

    • Hi Ricardo, Check to be sure that your test kit reagents or test strips are fresh, and that chlorine is not sky high, both which can give false pH readings. As you probably know, acid lowers pH and alkalinity levels, so to lower alkalinity, you often have to raise the pH afterwards. If you didn’t drain, I would raise pH first, to 7.6, and then use acid to lower the alkalinity. 100 ppm is not very high, the range is 80-120 ppm, in most cases. The higher the alkalinity is, the more stable the pH is, or harder to adjust.

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