Water Analysis: What We Test and Why We Test for It

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One of the most crucial steps to keeping your pool clean and clear this summer is balancing the water chemistry. It is no surprise that this task is dreaded by pool owners, having to determine the current levels for several different chemicals, then compare that to the recommended ranges for each chemical, then determining how much of each product to add to get properly balanced. That is why we like to offer free water testing to our customers. While many pool companies in Memphis have recently started charging for water testing, or have charged for it all along, we have always proudly offered water testing for free so that pool owners spend less time wondering how to balance their pool and spend more time enjoying their pool.

But just because we offer water testing for free doesn’t mean it is right. That is why, in this blog post, I want to go over the most common chemicals our retail stores test for when they run a water analysis, and why each of these chemicals is important.

Free Chlorine

Free chlorine (also called free available chlorine) is the measure of available chlorine in the pool. Even with the proper amount of physical chlorine added (through chlorine tablets, granular, liquid, or chlorine generated from salt systems), there are times when available chlorine levels are lower than total chlorine levels. When this happens, cloudy water can occur. Also, if the free chlorine level is below recommended levels, your pool water will not be sanitized properly. The recommended free chlorine level is 1 to 4 parts per million (ppm).

Total Chlorine

Total chlorine is the total amount of chlorine in the water. This level should be the same as your free chlorine level. If these two numbers differ greatly (measured as greater than 0.2 parts per million), then your pool could have chloramines in the water. Chloramines contribute to cloudy water, and to reduce chloramines it is recommended to shock your pool. The recommended total chlorine level is 1 to 4ppm.


pH is a measure of how acidic or alkaline the water is. The pH scale ranges from 0 to 14, with 7.0 being neutral. Values below 7.0 are acidic, and value above 7.0 is alkaline. The recommended range for swimming pools is 7.2 to 7.6. Incorrect pH levels can cause cloudy water and swimmer discomfort and will lower the effectiveness of chlorine levels.

Calcium Hardness

Calcium hardness is the measure of dissolved calcium in your swimming pool. Low calcium levels lead to pitting and etching in plaster pools, and faded or shrinking liners in vinyl pools. High levels of calcium will lead to scale build-up. The recommended level for calcium hardness in swimming pools is 180-500ppm.

Total Alkalinity

Total Alkalinity (TA), is the measure of bi-carbonates, carbonates and hydroxides in your water. The recommended range of swimming pools is 80 to 120ppm. Low TA will lead to erosion of the surface of concrete and painted pools. It will also cause unstable pH levels, which can result in major shifts in pH with small additions of chemicals. This is sometimes known as “pH bounce”. Lastly, low alkalinity can lead to stained pool surfaces and corrosion to pool equipment.

Cyanuric Acid

Cyanuric acid is the measure of stabilizer levels in your pool. Stabilizer is used to reduce the ultraviolet rays’ effect on your chlorine levels. By increasing your cyanuric acid level, you will increase the effectiveness of your chlorine. But be careful: each chlorine tablet already has cyanuric acid added to it, so you will not need to increase your stabilizer level. High stabilizer levels are bad for your pool and bad for swimmers. Stabilizer levels begin to limit the effectiveness of your chlorine once the cyanuric acid level is above 50ppm. Cyanuric acid levels above 100ppm can cause severe discomfort to swimmers and swimmers should stay out until the level is lowered. Recommended cyanuric acid levels are 20-70ppm.

There are several other chemicals that our retail locations test for, including salt levels, phosphates, nitrates, borates, biguanides, copper, iron, and metal sequestering agents (Jack’s Magic Blue Stuff / Purple Stuff). Each of these chemicals is invaluable to diagnosing certain conditions related to your pool and are tested for frequently. The chemicals detailed above are our main chemicals in our water analysis program that are essential to maintaining a properly balanced pool.

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