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Beginner’s Guide to Pool Water Testing

beginners guide to pool water testing

We have all heard of “testing the waters.” But when it comes to swimming pool care and maintenance, water testing is the best route to ensure you have an easy-to-maintain pool. It’s more than just eyeballing the water condition or touching the water to detect the temperature. Test kits, strips, and digital readers are used to check pool water balance levels.

Why Test Pool Water?

Without water, a swimming pool is just a hole in the ground. And without clean, clear, healthy water, swimming is just no fun at all.

Since swimming pools are generally used by multiple people at any given time, it is imperative to test and treat pool water regularly. Not only does it keep the water clean and prevent the spread of infectious diseases, it also enhances the pool experience and prevent damage to your pool and equipment.

What Water Tests Are Needed for a Pool?

In order for us to have a sparkling clean and well-balanced pool, we have to ensure that the water chemistry levels stay within the following ideal ranges:

aquachek-7-way-test-strip-color-chart
  • pH: 7.4-7.6
  • Total Alkalinity: 80-120 ppm
  • Calcium Hardness: 200-400 ppm
  • Free Available Chlorine: 2.0-4.0 ppm
  • Bromine: 3.0-5.0 ppm
  • Cyanuric Acid: 30-50 ppm
  • Metals: 0 ppm
  • Phosphates: 0 ppm
  • Total Dissolved Solids: 0-2500 ppm (non-salt water pools)

Of course, there are instances when test results might fall slightly outside of these ranges, and that’s usually OK! As long as you’re actively making adjustments to water chemistry and trying to maintain water in the ideal range, you’re on the right track.

Testing your pool water and maintaining perfect chemical harmony isn’t rocket science. However, it definitely involves regularity and consistency on your part.

How Often Should I Test Pool Water?

We recommend testing your pool water at least once per week. Add chemicals if you see an increase/decrease in ideal chemical levels. If you’re unfamiliar with your pool’s water balance trends, the pool is used frequently, the weather is exceptionally warm, you’re having water clarity issues, or if a storm recently rolled through your yard, you may need to test more frequently – at least 2-3 times per week.

pH and Free Available Chlorine levels should be tested more often, perhaps daily, until you come to a good understanding of how they fluctuate. Other readings for Calcium Hardness, Total Alkalinity, Cyanuric Acid, Metals, Phosphates, and Total Dissolved Solids, tend to move more slowly and can be tested weekly or even monthly in some cases.

Many basic test kits will at least cover your weekly testing needs. But you may need to purchase a more robust kit for monthly testing. You can also bring a water sample to your local pool store to gain a full picture of pool water health.

How Do I Test Pool Water?

There are several types of testing supplies available on the market, all varying in price and accuracy. It’s important to remember that certain factors will influence the accuracy of your water test. Ensure that your testing supplies haven’t expired, and keep them stored in a dry area at room temperature.

Circulate the pool on the pump’s high setting for at least an hour before pulling a water sample for testing. Test results from stagnant water may not be very accurate. Next, gather your water sample around elbow deep, or about 12-18″ below the surface. Avoid sampling near pool returns or floating chemical dispensers.

Once you have your test results, keep track of them. You can use a daily planner, dedicated pool calendar, or enter them into your favorite pool care app. Recording water balance trends will help you anticipate future changes in water chemistry, making it easier to maintain water balance over time.

Now that you’re familiar with how to test pool water, let’s take a closer look at the different types of water tests available.

Pool Test Strips

pool water test strips

Test strips are the most inexpensive and widely used method for testing pool water. They’re fast, easy, and fairly accurate. Some of the more basic strips can test for individual chemicals, or you can buy something like the AquaChek Select 7-Way Test Strips or Yellow 4-Way Test Strips to make multiple tests at the same time.

The most appealing feature of test strips, other than their low price, is that they are very simple to use. Just dip them in water, shake off the excess, and read the results within seconds. Test strips are usually color coded and come with an easy-to-read chart right on the bottle.

Liquid Test Kits

Taylor liquid dropper test kit for pool water

Liquid test kits are one of the most accurate ways to determine chemical levels in your pool. They’re higher in price compared to testing strips. However, liquid titration kits offer a more reliable and complete testing solution. Liquid testing kits make use of reagents, which are added to the water sample one drop at a time. Results are determined based on the number of drops and the color of the sample.

Liquid testing kits like the Swimline 4-Way Test Kit are economical and easy to use. Some like the Taylor Basic Residential DPD Test Kit take maintenance a step further, and include a dosage chart for translating test results into treatment. For a more complete water chemistry analysis, the Taylor Complete Test Kits are the way to go.

Digital Pool Testers

digital pool water tester

What is the first thing that comes to mind when you hear the word digital? Probably the words “accurate” and “fast,” right? When it comes to digital water testers, accuracy and promptness are exactly what you get. Extremely easy to use, the digital water testers often feature LCD displays, water-resistant housing, and even a memory function to view results history. Unlike other types of water tests, there’s no need for color matching on your part, so reading the results in digital format is a snap.

Digital pool testers come in a couple different types. Some, such as the Solaxx SafeDip MET20A, have electrodes that measure chemical levels in the water itself, and can provide an accurate measure of water chemistry. Another type of digital tester is kind of a hybrid tester, and uses either a test strip (AquaChek TruTest) or reagents (LaMotte ColorQ) to determine results. This second type of digital tester removes the margin of error associated with results determined by the naked eye, and can be especially helpful for pool owners with colorblindness. Of course, digital testers are more on the expensive side, but they provide a reliable, complete, simple, and fast water testing solution.

Which Pool Water Test Should I Get?

As a pool owner, you know that pool maintenance is not easy and does not come at the flip of a switch. Regular pool testing is an important step in preventing serious pool problems. All three of the water testing solutions above are a great way to test your water each week.

So now the ultimate question: should you use test strips, test kits, or a digital water tester? The type of pool test you use ultimately depends on budget and the level of accuracy you want in your pool tests. It’s a sliding scale between cost, completeness, and testing accuracy. Test strips cost the least with a marginal level of accuracy, whereas a liquid test kit costs more but has better results. Digital readers are the most precise of the three, and can help rule out [most] human error, but they’re often on the highest end of the price scale.

Here’s a tip used by many of our pool customers. If you’re looking to save money without sacrificing testing accuracy, use test strips for regular maintenance checks 2-3 times each week. Then use a more expensive liquid test kit once a week to confirm water balance levels and get a more complete picture. Fill in any remaining gaps with a professional water test at your local pool store. Some stores, like Leslie’s, offer free water tests.

OK, so what’s the best pool test kit? Below are some of our most popular test kits test strips in order of Fair, Good, Better, and Best. All of these tests are top quality. The main difference between them is the number of different water tests they perform. In terms of accuracy, the liquid drop-style pool test kits will always give more accurate results than test strips. But for quick and easy results on a daily or weekly basis, test strips are great for a general analysis.

Best Pool Water Test Kits

Fair: 2-Way Test Kit

  • Total Chlorine with OTO
  • pH with Phenol Red
  • Includes Clam-Shell Case
  • Inexpensive Starter Kit

Good: 4-Way Test Kit

  • Free and Total Chlorine with DPD
  • pH with Phenol Red
  • Acid Demand
  • Total Alkalinity

Better: Taylor Complete DPD Test Kit

  • Free and Total Chlorine with DPD
  • pH with Phenol Red
  • Acid Demand
  • Base Demand
  • Total Alkalinity
  • Calcium Hardness
  • Cyanuric Acid (Stabilizer)

Best: Taylor FAS-DPD Test Kit

  • Free and Total Chlorine with FAS-DPD
  • pH with Phenol Red
  • Acid Demand
  • Base Demand
  • Total Alkalinity
  • Calcium Hardness
  • Cyanuric Acid (Stabilizer)

Best Pool Water Test Strips

Good: Aquachek 4-Way Yellow

  • Free Chlorine
  • pH
  • Total Alkalinity
  • Cyanuric Acid

Better: Aquachek 7-Way Silver

  • Free Chlorine and Total Chlorine
  • Total Bromine
  • pH
  • Total Alkalinity
  • Calcium Hardness
  • Cyanuric Acid

Best: Aquachek 7-Way Select or Select Connect

  • Free Chlorine and Total Chlorine
  • Total Bromine
  • pH
  • Total Alkalinity
  • Calcium Hardness
  • Cyanuric Acid
  • Includes flat comparator, log book, and treatment guide
  • Mobile app available for digital analysis through AquaChek Connect

The best pool test kits will have the ability to test all five main water balance levels: pH, Total Alkalinity, Calcium Hardness, Cyanuric Acid, and Chlorine or Bromine. You may need to purchase specialty test kits or rely on professional testing to fill in the gaps for things like Metals, Phosphates, Salt, or Total Dissolved Solids.

84 thoughts on “Beginner’s Guide to Pool Water Testing

  1. Colin Miles

    My test strips using a digital reader give different readings evry time. The figures are greatly different and taken straight after each test. The digital reader is Aquachek. I was sold strips that are beyond the expiry date. Could this be my problem?

    • Colin, yes that would certainly be the problem. Expired tests cannot be expected to give valid results.

      • Colin Miles

        Excellent advise and great site. Thanks Davy. Best place to buy strips please?

        • Hi Colin, well right here at InTheSwim.com of course! 🙂 Here’s our AquaChek page, and we also have strips by Lamotte, Frog and Nature2. If you need something fast, check a local pool store, or in-season, at home stores like HD/Lowes.

  2. Hello I am having trouble with my pool. I just tested it with a test strip that test for free chlorine, pH, total alkalinity. My pool is a 18×48 above ground easy set pool. I have well water and it has a lot of iron in it. When I first filled the pool it was green, got that gone then it turned clear blue. After a lot is swimming with sunscreen on, the pool now is a really cloudy green-blue. I just tested it and the free chlorine is 0, the pH is 8.4, alkalinity is 240. I just put a half a bag of shock in it last night and the night before i put in muriatic acid. I change my filter everyday. I usually have chlorine floating in a floater. I took it out when I shocked it. The pool also has a yellowish film on the top. Please help!

    • Hi Shannon, the chlorine demand for the pool will increase with more sun, swimming and sunblock! When chlorine reaches zero, water quality goes south fast. And when pH is 8.4, only about half of the chlorine is working, and slowly, very lazy. Low pH (7.0-7.4) and high chlorine (2-4 ppm) is a good goal. If you are having trouble keeping chlorine in mid-day, you can add some Cyanuric Acid aka Stabilizer, to protect Cl from the sun. I also encourage Intex pools to use weekly doses of Algaecide and Clarifier, to help the small filter, and to shock the pool every two weeks, or for algae, cloudy water or if chlorine accidentally goes to zero. Your very high alkalinity level is making it hard to lower the pH, so you will have to add acid very regular, almost daily, to try to get it down by half, to 120 ppm. If your fill water (well water) is the same, as I think it is, you could consider draining and filling or mostly filling, by truck ($150-$250 in most areas).

  3. Rebecca Gardner

    I’m glad you explained that pool water should be tested on a weekly bases to make sure the chemicals are at the right levels. My husband and I just purchased a single-family home with a rectangular pool and small spa in the backyard here in Maui. Can’t wait to start taking care of the pool! We’ll be sure to buy our chemicals from you.

  4. Tom Penne

    I use your test strips on my spa. I have trouble interpreting the results. This morning, the ph patch on the strip turned pink. Is that on the ph high side or low side? I drained the spa and refilled it yesterday. I took a sample of the water to my spa dealer and their test indicated I should add 1 tbsp + 1 tsp of ph decreaser and one tbsp of stain and scale control. Need help with the pink strip?

    • Hi Tom, test strips are hard to interpret sometimes. Pink is generally a good color for pH, whilst red is too high and orange is too low. A taylor test kit would be my recommendation for accurate testing, that does not require a pool store to help. The Taylor Troubleshooter is a good value for $20.

  5. Mary Day

    I’m new to these test strips, my strips are showing Chlorine to be white, ph is peach color, total alkalinity is yellow, total hardness is purple, and cyanuric acid is a light yellow. Are these readings ok? Thanks, Mary

    • Hi Mary, I would guess that chlorine is zero and pH may be ok, but hard to say about the others, not having the color matching chart that the strip is compared to – which is usually printed on the bottle label, or on a separate piece of laminated paper, or also likely found on the manuf’s website.

  6. Deepak Gudadhe

    The pH value of my pool is 8.4 & the colour if waterblooks green. The temp is 43 to 45°. How to reduce the pH value & hiw to make water Cristal clear,please reply

    • Hello, lower the pH to 7.2 using a pH Decreaser (acid) chemical. Then shock the pool with granular chlorine, 2 or 3 lbs per 10000 gallons, or until the water turns a blue/grey color. Then lots of filtering, and maintain the good pH and chlorine levels.

  7. Sabrina Adkins

    When I test for alkalinity it took 15 drops swirling to tun the blue liquid to yellow. 15 x10 = 150. Does that mean I need to decrease or increase total alkalinity?

    • Hi Sabrina, 150 ppm is considered high in most cases, and high alkalinity can lead to high pH, or difficulty in adjusting pH. Most pools do well with alkalinity of 80-120 ppm. Add an acid to lower the alkalinity to around 100 ppm, after which you may need to raise the pH level. …

  8. Hi, my mom and I are considering moving to Arizona, and all of the apartments have pools. (I love to swim; you don’t even know!) My mother is worried about Legionnaire’s disease, so I think it would be a good idea to test the water, or at least ask the owner about the level of chemicals needed. My question is, how would we go about testing the pool water when we don’t own the apartments? I guess I mean what would be the steps to take?

    • Hi Lola, I would get a pack of pool test strips, the 4-way Yellow and then go to the pool, get comfy on the lounge chairs with your Mom, and then surreptitiously pull out a test strip, saunter over to the edge of the pool and have a seat on the water’s edge, dangling your feet in the water. Ever so cool, lean forward and palming the test strip so it’s not visible, move your hand (and strip) back and forth in the water for 10 seconds (or whatever time the test strips suggest), and then get up and return to your chair, and compare the results. Then you can say, “See, mama? the water’s fine…” 🙂

  9. Helene Shepherd

    Hi, I have very recently moved into a home with a swimming pool. I struggled to maintain the pool but after changing pool retailer to another more reliable and helpful retailer. However, I am still struggling to understand the test strips and what chemicals I should be adding. Would you be able to explain what each means and the more common name for the products:

    Total Hardness =
    Total Chlorine =
    Free Chlorine =
    PH =
    Total Alkalinity =
    Cyanuric Acid =

    I would really appreciate some help

    • Hi Helene;
      Total Hardness = How hard or soft the water is – water that is too soft can become cloudy or foamy, and too hard could produce scale or cloudy water. Best range is about 200 ppm.
      Total Chlorine = the sum of free chlorine and combined chlorine (aka chloramines), FC+CC=TC. Total chlorine should be the same as free chlorine. If it is greater that indicates the presence of combined chlorine, which indicates a need to shock the pool, at levels higher than 0.3 ppm of combined chlorine. If total chlorine is 0.3 ppm higher than free chlorine, shock the pool.
      Free Chlorine = the amount of chlorine that is free and available to kill, not combined with another molecule, which drastically reduces efficacy or killing ability. FC should be 1.0-2.0 ppm.
      PH = the ‘power of hydrogen’, or the relative level of acidity or basicity in the water. 7.0 is neutral, below is acidic, above is basic. Pools should run slightly basic, or 7.2-7.6, which is best for pool surfaces, chlorine potency and swimmer comfort.
      Total Alkalinity = the buffering capacity of the water in regards to pH. A close cousin of pH, it keeps pH stable. Too high and pH is hard to adjust, but when TA is too low, alkalinity is erratic and hard to control, Range is 80-120 ppm.
      Cyanuric Acid = stabilizer or ‘sunscreen’ for your chlorine. Used to protect chlorine from bright sun and make it last longer. Too much is a bad thing though, as it makes your chlorine sluggish, best range is 30-50 ppm.

  10. Richard Kraft

    Hi Cynthia Is there a system that analyses pool water and then adds the chemicals to the pool. I saw something called intellichlor by pentair that turns salt into chlorine. If I install that will I still have to add all the other chemicals

    • Hi Richard, a salt system like IntelliChlor will create the chlorine automatically, from pool salt added to the pool, but will not affect pH, alkalinity, calcium hardness or cyanuric acid levels, and won’t monitor those levels, so you will still need to test and adjust occassionally. Pool Controllers, such as the CAT 2000, or the Rola-Chem pH/Orp system, used with vats of liquid chlorine and pH chemicals, can maintain proper sanitation levels and pH control – but still not complete control, as it won’t affect calcium or cyanuric acid levels – but those two levels are slow to change and can be tested monthly.

  11. michelle

    Is it ok to test pool chemical levels when someone is in the pool swimming

  12. how do i raise the ph level in my pool?

  13. cynthia calderon

    Hi. I have no idea what to do but my above ground pool showed a reading (on a test strip) of FCI 10, BROMINE 20, ALK 40 and PH is yellow on the strip. What does that all mean?? Please help. T

    • Hi Cynthia, Test strips show both chlorine and bromine, but you can forget about bromine, since I presume you are using chlorine. Free Chlorine (FC) of 10 ppm is rather high, normal level is 1 to 3 ppm, but can go up to 10 ppm (or higher) when shocking the pool (aka superchlorinating). Alkalinity is Low at 40 ppm, proper range is 80-120 ppm. add alkalinity increaser to raise from 40 to 80. Yellow on the pH test means that pH is also low, recommended range is 7.2-7.6 y – add a pH increaser to raise. pH and alkalinity are closely related, so you may find that once you raise the alkalinity, that your pH level will also rise, perhaps into the normal range.

  14. Jennifer

    Hello
    I’ve had my pool for about 2 1/2 months. We filled with well water from our house. I have kept 1lb of shock in it every wk up until now when I realized I should be using 2lbs. I have also been using 1 of the chlorine tabs and now have doubled. My pool size is 18×24 so around 10,000 gallons. It also has a sand filter. I was advised after numerous tests with it being a complete reading of 0 on the test strip, to also use alkalinity. So today I’ve added 2 of those as well to the floater. I shocked my pool on Sunday with 2lbs and checked today (tuesday) and I still get a 0 reading for everything. I’m using 6 way test strips. My pool has turned a very light green twice since I’ve had it but I’ve always used shock to get it back blue. I dont understand why I continue to get a reading of 0 on everything. Please help! Thank you in advance! 🙂

    • Davy Merino

      Hi Jennifer, maybe the test strips are bad or expired, if you are getting ‘0’ for readings, that may not be likely with exception to chlorine, which can go to zero very fast. Second thing I would ask is how long are you running the filter each day? During the heat of the summer (now), you may need 15-18 hrs daily, if your filter is on the small side, or under 21″ tank diameter. So now you are using 2 of the 3″ chlorine tablets each week, and 2 lbs of shock each week? That sounds like it might be enough tablets to give you a constant and consistent chlorine reading of 1-2 ppm daily, and two bags of shock should take it up to near 20 ppm, which is a good shocking. Just be sure the pH is 7.2-7.6, and the alkalinity 80-120 ppm, and calcium hardness is 180 ppm or higher. Also important during summer is a good level of stabilizer, aka cyanuric acid, to protect chlorine from the sun. 25 ppm to 50 ppm is normal. And… don’t add anything to the chlorine floater except tablets. If you mix other chemicals with the chlorine tablets, you could have a very bad day!

  15. hi tested my pool with strips today, it says everything is low but the alkalinity is normal. first can we swim with it like that and second if we can not will a chlorine tablet be enough to stable everything?

    • Hi Krystal, the most important things are pH level and chlorine level. For safe water, a pool should have a good pH level so that chlorine is able to work most effectively – high pH levels make chlorine very lazy, so just be sure that chlorine is below 7.8, and preferably 7.4-ish (all the time). Secondly, make sure the chlorine level is 1.0 ppm minimum, up to 3.0 ppm, to kill bacteria, algae and other pathogenic microbes. Use enough tablets, to produce a consistent and constant chlorine level, as verified by your test strips. To be double-sure that water is disinfected and sanitary, use a granular pool shock regularly, every few weeks to superchlorinate the water, to kill anything that has escaped your daily chlorination from tablets.

      • thanks for your reply. i used a shock treatment before the tablet and the tablet has been floating for 2 days and is normal now but the ph is still low. how do i bring just the ph level up? thank you!

        • Hi Krystal, with such a small pool, a low pH may not be an issue, unless it is very low, 6.8 or less. If so, add pH increaser, aka soda ash, to raise pH. You can use poolcalculator.com to compute small amounts needed.

  16. We have the liquid test kit (just yellow & red)and when testing our pool our red ph is almost clear, and our yellow cl is red or
    ange. What are we doing wrong & what should we do now?

    Please help, Thanks!

    • Hi Melissa, that sounds like bleached out pH test from a very, very high chlorine level. OTO test kits are normally yellow-orange for chlorine (DPD kits are pink-red). pH tests will ‘bleach out’ from a very high chlorine level. For test kits that also test Total Alkalinity, you can use the #7 reagent (Taylor kits), or the first Alk test reagent, sodium thiosulfate, to neutralize the chlorine in the pH water sample, just a few drops. Once your chlorine level drops to within more normal range, your normal test results should return.

  17. We finally got a sand pump and are trying to open our pool. We got the green yucky color out but now it’s a cloudy blue color. After pouring 2lb of shock, My test strips say it’s good on the chlorine but reads low on the pH and the alkalinity. Please tell me how to fix it!

    • Jessica, you are almost there! Just keep the chlorine level high, and run the filter non-stop, backwashing only when pressure rises 8-10 psi, or flow rates slow noticeably. Don’t worry about pH/alk at this point. Sand filters can pass very small particles, so you may want to use a Clarifier to help coagulate small particles so they can be filtered more easily.

  18. How long do the digital testers last? Do the electrodes become ineffective after some time? Thanks.

    • RJ, thanks for the question. Most electronic sensors do go bad after some time, however test sensors are only exposed when testing, so one might presume that the electrodes could last a very long time, if kept in good condition. It’s been a long time since I have used a digital tester, so I can’t answer with any authority, but I would expect the device itself might fail before the electrodes would.

  19. Monique Mojica- Aponte

    Hi I have a inground pool and I tested my water today and it’s been 1 week and half since I opened it . All the readings on the hach aquacheck 7 are in ideal or ok range except for the cyanuric acid which is super high? What do I do pool ownership is brand new to me.

    • Hi Monique, cyanuric acid is best at 30-50 ppm, when approaching 100 ppm, chlorine becomes very lazy and hard to get a reading, and then algae and cloudy water can result. If your water is clear and shiny, no worries. Test strips can also be a bit inaccurate on the cya test. If it is too high, dilution is the solution – or use the BioActive cyanuric acid reducer chemical.

  20. Laverne fubara

    hello, I have a in 1 test kit with these readings and still green water.

    last night I added 1.5 pound of shock and a pound of stablizer
    chlorine 2.0
    free barely changed 2 minutes later, maybe .5

    ph 7.2
    so demand was not done
    alkalinity 60

    should I just add ome clarifier at this point?

    • Hi Laverne, if the water still is green, I would shock again, adding enough until it ‘bleaches out’, and turns a blue-grey color, might take 1, 2 or 3 lbs per 10,000 gals (or more) depending on the shade of green. If you can see the bottom of the deep end, 1-2 lbs, if you cannot see the shallow end, 3-4 lbs (per 10K gals). Then wait a day or two, then add the clarifier, after the chlorine comes down again.

  21. Hi Britt – Free and Total chlorine should be the same, optimally. When they are different, when Total is darker than Free, that indicates the presence of combined chlorine, or chloramines TC-FC=CC. Shocking the pool to 10x the level of CC is required to restore order, breaking the chlorine compounds apart. So for CC of 1.0, shock the pool to reach 10 ppm, using 1 lb of shock per 10,000 gallons, plus a little extra, just to be sure. Alkalinity and pH look good at 80 ppm and 7.2. Total hardness is not likely at zero, I’m not sure if that’s even possible. Retest, and add calcium increaser if the levels are below 200 ppm, or 150 ppm for vinyl pools (minimum). Cyanuric acid, aka Stabilizer, is optional – stabilizer protects chlorine from the sun, allowing it to last much longer. Recommended for sunny pools, 20 ppm minimum, 50 ppm maximum. Add 1 lb stabilizer per 10K gals, to raise 10 ppm.

  22. Hi there! I feel like I’m needing a lot of help. We opened our above ground 30 foot pool a couple weeks ago (cartridge filter) and have yet to get it clear. We were fighting iron and it always stayed cloudy blue. We had been working with our pool store and had recently dumped in 4 gallons of liquid chlorine to actually get a chlorine reading. This past Saturday our pump broke as the temps soared to mid 90s! The water turned to a green color now. We have been using our robot sweeper constantly to sweep up anything and don’t have any algae on the floor anymore. Our new pump is finally running and upon testing everything, here are the results:
    Total Bromine: 0
    Free Chlorine: 0
    pH: 6.8-7.2
    Total Alkalinity: 80-125

    What are the next steps we need to take to get our pool crystal clear?

    Thank you so much!!

    • Add chlorine! zero chlorine seems to be the current issue. Add enough pool shock or liquid chlorine to raise the chlorine level to around 10 ppm, or until it turns a blue-ish color. Keep running the filter, non-stop, and clean as needed to keep flow rate strong.

      • Thank you so much! Adding another 4 gallons of liquid chlorine? And then when it turns a blueish color, what is our next plan of attack to get it clear? Testing and balancing?

        • Hi Ashley, yes shock again 4 gallons of bleach, or 4 lbs of shock, brush the pool, and filter continuously. Small filters, which can be suitable for normal operation, sometimes do poorly with algae clean-up. Cartridge filters and Sand filters can use a small amount of DicaLite (perlite) as a filter aid, which coats cartridges and sand beds, to add another medium layer, and trap smaller particles. Another helper is the Slime Bag, funny name, attaches to the return line jet, and the fine mesh bag acts as a secondary filter. Using a Clarifier is another method to improve filtration.

          If you have a pool cleaner, running it can help circulation, otherwise skim, brush and vacuum while it clears up. And, as you mention, keep testing the water to monitor chlorine level, stabilizer level, and pH / Alkalinity levels. Don’t backwash too often, or clean the cartridge before it’s really dirty – a dirty filter is actually a better filter than a clean one, until such point as flow rates begin to diminish. The rule of thumb is to clean the filter when the pressure gauge rises 8-10 psi above the clean, starting pressure.

          • We added the 4 gallons of liquid shock last night and have been cleaning our filter and using our robot vacuum as well. The water this morning is still quite green and I tested it.
            Total Bromine: 10 (high)
            Free Chlorine: 5 (high)
            pH: 7.2
            Total Alkalinity:125

            Do we need to keep super shocking it to get rid of the green and raise the Chlorine higher? How much more should we add if we need to? Do we focus on raising the pH first (what is best for that?? Borax or Baking soda?)? Do we need to use an algaecide?

            Thanks for your help!!

          • Hi Ashley, don’t worry about the bromine reading, when testing it is either/or… the test kit can be used for both bromine and chlorine, bromine is always twice chlorine, because it’s twice as ‘heavy’, so 5 ppm chlorine is not high enough – perhaps the liquid shock you are using is not that strong (normal pool bleach is 12.5%, household is 5%), or has lost potency, which liquid bleach does within a few months of manufacture. So you may need 10 gallons…? Keep adding until it turns blue/gray. Granular shock may be easier, especially our Super Shock (73% strength). Algae removal generally requires 10 ppm to 30 ppm, depending on how ‘thick’ is is, or how poor the water visibility. Light green pools can shock to 10 ppm successfully, medium green may need 20 ppm, dark green–30 ppm.
            Don’t use an algaecide until the chlorine is low – it’s best for prevention and control, not for killing algae (despite the name ‘cide’), Use chlorine to kill, algaecide to control. Your pH and Alkalinity are good at this point, just focus on getting enough chlorine in the water to turn the pool blue (instantly, within 10 minutes, or keep adding more). You have to reach a threshold where the power of the chlorine is greater than the consumptive power of the contaminants. Hit it Hard! 🙂

          • We ended up adding 10 gallons of liquid shock. We also ended up replacing our cartridge filter and getting a new one as well. As of now, everything is testing HIGH and the water is a light green and cloudy. Our filter/pump pressure is being monitored and the filter cleaned when needed. Do we just continue filtering until clear and levels drop?

          • Hi, yes keep filtering, let the solids build up in the filter before cleaning, or until the pressure gauge is about 10 psi higher, or flow rate noticeably diminished. Using a pool clarifier or adding a cup of Dicalite to the filter could aid in faster clean-up. Keep checking chlorine daily and pH, to be sure chlorine stays about 2-3 ppm, and pH stays 7.2-7.4. Almost there! 🙂

  23. Alaina Siefker

    PH is 7.8, free chlorine is 3, total alkalinity is high between the 180 & 240, stabilizer is low. Pool is above ground 24’.

    • Hi Alaina, Add pH decreaser to lower the alkalinity to around 100 ppm. This will also pummel your pH level, so when pH gets to 7.0, add pH Increaser to raise pH again to 7.8, then the following day hit the alkalinity again with pH decreaser. This may take a week of once or twice daily adjustments, back and forth in this manner, to lower both pH and alkalinity to proper range.

  24. Hi I have a 12 by 30 pool and my chlorine test is orange what do i do

    • Orange? I guess that means it is very high, if you are using an OTO test kit (normally yellow results). Just leave it uncovered and run the pump to keep it circulated and the chlorine will drop naturally over the next 2-4 days. Remove any chlorine tablets you have in a floater or chlorinator, until levels drop to between 1-2 ppm, then add them back again. Keep testing everyday, until color stabilizes or gives you a normal reading.

  25. Deborah King

    First time Oklahoma pool owner here! Bought a Summer Waves 17×54 frame pool, roughly 6400 gallons. Filled slowly over 4 days with well water. Added chlorine tab floater at half way point. Once full and hooked up the pump the pH and Alk tested hi 8.4/ 240. Hardness was also high and expected at 1000 it is now down to 500. Had a hard hard rain that helped topped pool off, the pH then plummeted to 6.8,l before I could add the pH Down chemical and the Alk has stayed high. I’ve added Stabilizer/ Metal, Scale Remover, twice, and shocked it once thus far. The tests have been all over the place from hi to low. Wondering if the high Alk is my bugaboo or?! The water is crystal clear. No signs of algae, slime or cloudiness at all. I run the pump around 4 hours twice a day, longer when adding any chemicals. I will be investing in a better way to test soon just would like to learn more about the process and brands beforehand. Here are my current readings
    Hardness 500
    Ch 5
    FC 3
    pH 6.8
    Alk 240 get same reading everytime
    Stabilizer 50
    I have not added arm & hammer soda yet as I read it can raise the Alk by far. There is a lot of info available on line yet, it becomes confusing and contradicting to a point! Any advice is greatly appreciated!!! I so do not want to fail at this, with our heat and humidity this pool is an awesome addition to home and a great way to cool off! Just wanna do it safely 🙂
    TIA

    • Hi Deborah, the Alk at 240 ppm is rather high. Such high Alk would make moving the pH very difficult. You said the pH was at 8.4, and then after the (acid) rain, it fell to 6.8? If it stayed low, I would think that the Alk reading may be false, or could be messed up from the high calcium levels interfering with the alk test. If you have your pH in a good place (7.2-7.6), and it stays stable, don’t worry about alkalinity. And yes, don’t add baking soda, as that is used as an alkalinity increaser. Also noting your Ch (total chlorine?) of 5.0 and Free chlorine of 3.0 – when total chlorine and free chlorine are different, the difference is combined chlorine or chloramines. If over 0.5 ppm difference (if total cl is darker than free cl reading), then it’s a good time to shock the pool, to a level 10x the CC level, to break apart chloramines, which get in the way of sanitation and make the water smell chlorine-y, and sting the eyes.

  26. I have a 5000 gallon above ground pool. Using a test strip, my chlorine Is perfect, but my pH, alkalinity and cyanuric acid readings are zero. I keep two floaters with the chlorine tablets in the pool, at all times. What do you recommend?

    • HI Becky, I would recommend new test strips, or even better, a test kit with dropper style reagents. It is not possible to have a zero pH and unlikely that alkalinity is at zero as well. Cyanuric acid could be at zero, if you did not add any, but if you use stabilized tablets, it would also be unlikely. Test strips last about 2-3 years, but can be damaged by moisture, heat, or direct sun.

  27. Brittany

    We just bought 1000 gallon pool. We tested it last night PH was 8.4 and total clorine was 0. Hardness was 500. Stabilizer and free clorine were good. So I added a 1/4 a cup of oh lower and 3 tablespoons of scale and hardness solution. And 5 tsp of clorine. Tested it 2 hrs later no change. What am I doing wrong? Please help!

    • HI Brittany, check the total alkalinity level, it may be too high or too low, best range is 80-120 ppm. Once the alkalinity is correct, you should be able to lower the pH effectively. And, once the ph is down to about 7.4 you should be able to establish a good chlorine level.

  28. Michael West

    I have test the pool, it reads total hardness around 180, total chlorine around 0-0.5. free chlorine 0, ph 7.3. total alkalinity 90, cyanuric acid 30. what do I need. The water right now is clear.

    • Hi Michael, sounds perfect in terms of water balance, you just need to get the chlorine reading up, a constant and consistent 1.0-2.0 ppm at all times, using chlorine tablets. You can also use granular chlorine to raise the chlorine level quickly, 1 lb of shock in a 25000 gal pool will boost it up to about 3-4 ppm, and then as it drops, the tablets will dissolve to keep the level above 1.0 ppm. Use your chlorine test kit to determine the correct number of tablets needed at any time, usually about 2 tabs per 10000 gallons, per week, replacing them as they dissolve.

  29. deborah deubert

    Hi I to this hot tub stuff but I sure like it. I have not mastered on how get the water balanced correctly. So to start I am using aqua check test strips. First question is does it matter if more than one chemical added at a time? Additionally the biggest issue right now is for me to understand that if the ph is off, like really off, (it is often purple) does that mean it needs to come up or down? I have both a ph increaser chemical and a ph decreaser chemical. Then assuming I eventually get an accurate ph reading do I then look to acquire accurate readings of the other chemicals? Please help… thanks. DD

    • Davy Merino

      Hi deb, When pH is really purple that means that it’s too high, or basic, when it’s really yellow, that means it’s too low, or acidic. Anything below 7.0 neutral is more acidic on the pH scale and anything above 7.0 is turning basic. The best range for pools and spas is 7.2-7.4. Too high and scaling and cloudy water can occur, and sanitizers are very slow to react. Too low and staining and corrosion can occur from acidic water. Use the pH decreaser if pH is above 7.8, and use pH increaser if it goes below 7.2. If it seems to bounce around a lot and your pH is ‘erratic’, check the total alkalinity, it should be 60-80 ppm in high calcium hardness water (over 400 ppm) or 100-120 ppm for soft calcium hardness water 150-200 ppm. However, for a Purple pH test result, it could be that the sanitizer level is so high that it is interfering with the test, if you suspect it is, you can dilute the test solution by half, but only with a test kit, not test strips.

  30. I bought a 15′ x 48″ round Intex pool (blow up top ring) a couple of weeks ago. I am having a hard time with the testing. I filled the pool with well water running through an in-line hose filter. The filter with the pool is 1000 gph. When the pool was full, I put .5 lb of shock in it which was the recommended amount. A few days ago, I put in another .5 lb of shock. I am using a floater with 3″ tablets. My pH, alkalinity, and chlorine levels are very low. I tried adding baking soda and that helps a little. I tried putting more than 1 chlorine tablet in the floater. I have tried 2 different testers (Poolmaster strips and Taylor test kit). The pool water is clear and no slime on the pool walls or floor. We swim almost every day. Besides the readings being very low, everything else is good. What am I doing wrong? (sorry for the long post)

    • Davy Merino

      Hi Renee, thanks for all the info, prefer long posts… likely you have very low stabilizer level (Cyanuric Acid) in the pool, and if testing during sunlight hours, it may be very low (chlorine). Adding 2 lbs of stabilizer would raise the cyanuric acid level to 20 ppm, per 10,000 gallons. Secondly, I would double shock the pool with an entire bag of shock, in the evening. If the chlorine level rises and remains for at least 8 hours, still there in the a.m. – good. If it’s zero again, repeat the dose, but double it to 2 lbs of shock – trying to reach a breakpoint threshold where whatever is consuming the chlorine is eliminated. Then raise the pH level using pH increaser, baking soda will also work, but will raise alkalinity more than pH. As long as you can keep it 7.2-7.8 (pH), it’s good. Below 7.0 and the water becomes slightly acidic and below 6.5, it will begin to eat your pool 🙂

  31. Have a sand filter thats stopped working that is now fixed my pool was almost clean just cloudy but itnis. Ow green the walls are not slimy i added 2 bags of shock and let the pump runnfor 24 hours while backwashing here and there. No color change at all what do i do. Also whem do i use ph kit and do i had increaser before or after addimg different shock treatment

    • Hi Sam, test your pH every few days, or at least 1x per week. Chlorine works most effectively in the 7.2-7.4 pH range. When it’s near 8.0, chlorine is very sluggish, and over half of it is impotent. Resist the urge to backwash, until filter pressure has risen at least 5 psi – sand filters work better when they are a little dirty. Using a clarifier could help clear the water. When shocking for algae, have a low pH, and keep adding shock until the water turns a blue/grey color, depending on the severity, it can take 2,3,4 or more lbs of shock, per 10000 gallons of pool water. When it turns blue-ish, with no hint of green, add one more pound, for good measure, brush the pool and run the filter all night.

  32. I use a test strip to test the water in my above ground 15×30 pool. The chlorine level shows almost white (very low) although the total chlorine seems to be at a good level. I did two tests just to make sure. How can that be? What should I do to adjust it? All other readings look good. Hardness is a little low. I shocked the pool last week and have also added powdered chlorine a few days after that.

    • Hi Bob, total chlorine is made up of Free chlorine + combined chlorine. If your total reads high, but your free reads low, the difference between the two is chlorine that has combined with something, to be the dreaded ‘chloramine’ – no longer an active sanitizer, and responsible for strong chlorine smell and red eyes. The solution is to add enough shock chlorine all at once to break apart the molecular bonds holding your chlorine hostage. For a 15×30 pool, around 10K gallons, I’d go with 3 lbs off shock, predissolved in a bucket of water, and poured around the edge.

      • The shock chlorine link you have in your comment above says NOT to dissolve in water. Is there a reason you say to dissolve it first?

        • Hi Bob, I believe that to be an error, and I have alerted the web team to correct. For any vinyl pool, pouring shock directly in the pool can cause the liner to bleach or fade, over time. Wont’ normally happen if you do it once (although it may). So, I advise to fill a clean 5-gal bucket with pool water, then pour the shock in, and use a stick or rod to stir to dissolve. Then pour in the water, but when the bucket is almost empty fill again with water, to dissolve remaining granules. Plaster or concrete pools and maybe fiberglass dont’ need to pre-dissolve, but for painted pools and vinyl pools – it’s a good idea to do so…

  33. Hello. I have a 5300 gl round pool I just started and have never had a pool before. I shock the pool yesterday afterwards 6pm and in the morning test the water with a strip. I am using a floder with a 3′ chlorine tablet and have the setting on hight the tablet is for a 10000 gl
    Chlorine is 10
    Chlorine free is 10
    Total hardness is 500
    Ph is 6.8
    Total alkaline is 120
    Stabilizer is zero
    What should I do Please help thank you for your time

    • Davy Merino

      Hi Tyson, sounds like you are grasping it, and you’re almost there. To protect chlorine from the sun, add a small amount of cyanuric acid, just 16oz, or 1 lb, to build up a residual. then secondly I notice hat your pH is low and alkalinity high. Add pH increaser, about 2 lbs of soda ash, to raise pH level to 7.4 range. The chlorine is very high from the shocking, but should come down today/tomorrow, then your tablets will maintain the level, in the 2-3 ppm range. Hardness is quite high, but not much you can do about that, should not be a problem. Sounds like you’ve almost mastered the chemistry, the other thing to pay close attention to is the amount of daily filtering and circulation. Your filter may be a bit on the small side, and you may need 18 hrs per day of filtering, or more, to compensate. Use a timer for best results, so you don’t forget to turn it back on!

  34. Hi

    I tested my pool for alkalinity this morning using an electronic tester one side read the alkalinity ar 120ppm the other side read 170ppm is this possible. Ph is looking w at 6.7. I’m finding it difficult to regulate the ph due to the alkalinity.

    • High alkalinity and low pH is one of the most troublesome conditions to deal with. You need to lower the pH to also lower the Alkalinity (using pH decreaser or muriatic acid), and then your pH goes too low, and you need to raise it back up, but the high Alkalinity fights the change in pH, by buffering the pH too much. It may be cheaper and easier to drain half the pool, refill with source water of a lower alkalinity and higher ph (use your test kit to test your hose water). Otherwise, buy the large bucket of pH decreaser, and the large bucket of pH increaser, and treat the pool each day over the course of a week, and you should be able to realign the two.

  35. Jackie Pitre

    Good morning! I tested the pool and seems like everything was in balance but water is greenish color. You can see the bottom but water is green. Its not slimy but I bought the yellow mustard chemical and put in the pool along with 2 lbs of chlorine. This morning still the same vacummed it and according to strip there was no chlorine so I added 2 lbs again of chlorine. Not sure what to do next.

    • Hi Jackie, keep adding chlorine shock until you see the water turn a blue/grey color. For dark green pools that can be over 10 lbs of pool shock. I would avoid yellow out (sodium bromide) and just use lots and lots of shock, with the pH on the low side (7.1-7.3). When the chlorine level drops to zero the morning after a shock treatment, the chlorine demand was higher than the treatment dosage. Double it and try again!

  36. STEVE GARGUILO

    my ph test kit is bright yellow do add ph+ or ph-

    • Davy Merino

      Hi – on most pH tests, yellow colors indicate low pH, and thus requires pH+ to raise the pH. ‘Bright’ yellow may also mean that the reagents are expired, or that the chlorine level is very, very high.

  37. […] of pool! I’ve spoken on the topic of pool water testing before, and we also have a nice beginner’s guide to pool water […]

  38. […] require frequent chemical testing and adjustments. Altering the pH levels consists of adding acid to lower pH or adding a base to […]

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