Water Quality in your Intex Pool – Testing & Measuring

Testing & Measuring Basics

Keeping clean water in your requires that you maintain correct water chemistry. Although the word “chemistry” may seem intimidating, the process is actually very simple. There are four or five measurements to take, and some simple actions to take based on that information. The four key properties to monitor are Chlorine Level, pH, Alkalinity, and Calcium Hardness. Pools that use a saltwater chlorine generator will also require salt levels to be measured. Continue reading to learn about basic test kits, or you may skip directly to our recommended kits.

Handheld Electronic Testers

Recently, a few companies have produced electronic pool water testers. These handheld devices claim to make water testing as simple as pressing a button. The results are displayed on an LCD screen, which provides quick water chemistry feedback. One of the more popular devices available is the Solaxx MET01A. As you might notice, the reviews on this device are a bit mixed, with several buyers complaining about the accuracy of measurements. At this point, it seems that we aren’t quite to the point of using electronic devices for testing pool water.

Basic Test Kits

The water test kit included with Intex pool kits will typically measure two of the four or five levels that need to be monitored – Chlorine and pH. These basic kits use paper strips with special patches that change color after they are dipped in the water. A similar type of test uses red and yellow droppers to add a chemical to samples taken from your water. Tests of this type are known as “OTO” tests because they use chemicals known as orthotolidine.

After a few minutes, the patches change to various shades of red and yellow. The dropper type tests will cause the water samples to change to red and yellow colors. The colors on the patches or in the water samples are compared with colored squares on a sticker or sheet of paper in the kit. The matching the color on the strip has a number next to it that indicates the approximate Chlorine and pH levels in the water.

While these kits are often free with a pool package and are inexpensive to replace, the problem with them lies in their lack of accuracy. Matching shades of yellow and red from a wet strip to a card or sticker is a very subjective method of taking a measurement. This method is very dependent on the user’s judgement, and results can vary based on things such as whether the readings are taken inside under artificial light, or outside in sunlight. Additionally, the chemicals used for this test eventually expire which further reduces accuracy.

At best, OTO tests provide a quick way to get a rough idea of pH and Chlorine levels in your pool. However, they do not really provide the accurate and reliable measurements that you need to successfully manage your water chemistry.

Recommended Test Kits

In order to truly understand what’s happening in your water, you will need a professional quality test kit. These kits will measure Chlorine accurately up to very high levels. They also measure Stabilizer/CYA, Alkalinity, and Calcium Hardness. This allows you to monitor all four of the critical chemical levels in your water. The list below contains links to a few of these quality test kits on Amazon:

These kits are known in the industry as FAS-DPD and while they cost a bit more than the standard OTO test kits, they are substantially better in terms of quality, accuracy, and test range. FAS-DPD is an abbreviation for the two chemicals used as reagents in the test – “Ferrous Ammonium Sulfate – Diethyl-P-Phenylene Diamine” (quite a mouthful!). Don’t let the complicated name intimidate you, the tests are fairly simple to perform and they will help you to better understand how good water chemistry works.

To perform these tests, you basically take a water sample from a few feet below the surface and separate it into a few test containers. Powders are added to the samples and mixed together, and then drops of chemicals are added and counted. After a certain number of drops are added, the samples will drastically change color. The number of drops needed to change water color is multiplied by a fixed number, and the result tells you what the measurement is.

FAS-DPD tests are reliable and accurate because the change in the color of the sample happens quickly and is impossible to mistake – almost like a light turning on or off. Because of this unmistakable change, there is no judgement call or shades of a color to judge. As long as you count the drops correctly, you will have an accurate measurement.

These kits include good instructions, and the most common & important measurements can be taken in about 5-7 minutes. With the test tubes and precise testing methods, you will also look like a chemist or mad scientist, which will surely impress family or friends. Eventually you will need to replace certain chemicals in the test kit, and these are usually available at pool stores or online.


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