How do I test and treat my pool water?

Tips & Tricks


Question: How do I test and treat my pool water?

Testing your pool or spa water regularly is probably the most important action that you can take to keep your pool operating properly. At Sutro we’re working on the next generation of water testing - highly accurate and automatic testing - the Sutro Pool Monitor will do all of the hard work for you. In the meantime, tried and true manual tests are still the way that most people will test their water. Let’s look into the types of test kits, what they test, and how to use them.

Test Parameters


There are 5 main parameters that a test kit will test your water for:


  • Free Chlorine (FC) - the amount of available chlorine in your pool water - measured in parts per million (ppm). Typically treated with chlorine.
  • pH - pH is a measure of the acidity or basicity of you water - whether it’s acidic, basic, or neutral. A pH of 7.4 is usually the target for pool water. Typically treated with muriatic acid (lowering pH) or soda ash (raising pH).
  • Total Alkalinity (TA) - TA is a measurement of all carbonates, bicarbonates, hydroxides, and other alkaline substances found in the pool water. Maintaining a proper TA level is important for keeping pH stable - Alkalinity keeps the pH from swinging drastically over time. TA should be kept in the 80-120 ppm range. Typically treated with Sodium Bicarbonate (baking soda) to raise TA levels and acid to lower levels.
  • Cyuranic Acid (CYA) - CYA is often known as Chlorine Stabilizer. It is used to protect chlorine from the sun’s UV rays, allowing the chlorine to be effective for longer periods of time. Typically CYA should be 2-4 ppm. Treated by adding CYA to water.
  • Calcium Hardness (CH) - CH refers to the amount of calcium that is in your water. Low levels of calcium in your water can cause the water to leach calcium from elsewhere - namely your pool lining. So keeping CH in line is important for your pool’s longevity. CH should be in the 150-350 ppm range, depending on the type of pool lining you have. Typically treated by adding calcium chloride to your pool water.

Test Kit Types

Test Strips


The first type of test kit is the venerable test strip. You simply dunk it in the pool water and match the colors on the strip to a chart that comes with the kit. Test strips are great for quick and easy water testing, but they can be much less accurate than other methods

Drop Testers


The next type of test kit is the drop test kit or reagent test. Drop test kits are more complicated to use then test strips, but when used properly they produce more accurate results.


Drop testers use various chemical reagents that react with pool water to create a visible change in the water.

Many of the drop test kits have varying directions, but in general, you take a sample of pool water and drop a chemical reagent in various combinations and amounts into the water - the water changes color and these colors are matched to a chart which tells you the level of a particular parameter.


While more time consuming and complicated then the test strip - when used properly, the drop tester is a great tool for accurate water testing.


 Treating  your pool



After you have your test results, what do you do? Typically, you break out the dosing chart that comes with the test kit or your pool chemicals and try to figure out what you should put in your pool water. Usually, the charts say - for x gallons of water and y test reading, add z quantity of our chemical.


We have a better way!

I would be remiss if I didn’t take this opportunity to point out a great FREE tool that we have developed to help you use treat your pool water. is a chat bot that eliminates the need for the dosing chart. You tell us a little about your pool - mainly the number of gallons and water type and can tell you what to put in your pool. It’s simple and fun - and did I mention FREE! So check it out and sign up at

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