Techs must be able to test and track an array of factors. Fortunately, modern science has provided nearly as many methods with which to do it.

Trouble is, just keeping track of the various testing methods and how they apply is enough to test a tech's patience.

Here's a rundown of the various tests at your disposal and how to complete them accurately.

Titration Tests:
These typically measure pool water's total alkalinity (TA) and its calcium hardness. They utilize reagents (chemicals) that are dropped into the water sample and bring about a change in color. The variable here is not the hue of the color, but rather the number of drops needed to change the color. Each drop correlates to a specific level of the factor being tested.

Colormatic tests.:
Perhaps the most common type of test, it's designed to measure the amount of sanitizers (such as chlorine or bromine) in the water, as well as determine pH levels. Here, reagents are added to a water sample. The resulting color is compared to a chromatic scale known as a color comparator. This scale will indicate the pH or chlorine level of the water.

Test strips:
Another test method quite popular with residential pool service techs, these strips are dipped into the water sample. This lets the reagents on the strip react with the chemicals in the water. The reaction will change the color of the pads on the end of the strip. Again, a color comparator quickly shows the level of the factor being tested. Test strips can measure sanitizer, pH, acid, and base demand, calcium hardness, TA and metals.

Turbidity tests:
Commonly used to measure cyanuric acid (CYA) levels, these tests rely on reagents as well. The reagent reacts with the chemical being tested to create turbidity rather than a color. The relative cloudiness of the water is used to generate a reading.

Electronic tests:
These are basically meters with electrodes designed to read levels of specific chemicals or other pool-water factors. They're often used to test sanitizer levels, TSD and, most commonly, pH. The meters must be constantly calibrated, and the electrodes must be kept clean for accurate results. They're also more expensive than the aforementioned test kits, but some techs say they save time and are worth the money.

Searching for Chlorine

The most important, and therefore most common, test service techs must perform is determining sanitizer levels.

Without the right amount of chlorine, or in some cases bromine, a swimming pool can become not only aesthetically undesirable, but dangerous to swim in as well.

There are two common methods employed by service techs to measure chlorine residuals in swimming pools.

DPD:
(diethyl-p-phenylene diamine) This is a chemical reagent that reacts with free, or active, chlorine. The sample water is combined with the DPD reagent in a test vial. Between 1 and 3 ppm, the NSPI-recommended chlorine levels, the sample will turn varying shads of red.

One note of caution when doing DPD tests for chlorine: With high chlorine residuals (10 ppm and up), the reagent will bleach out and the test will actually resemble low chlorine. At this point, a tech is likely to add even more chemicals to the pool when the levels are too high already.

If you're suspicious of this phenomenon, simply dilute the test sample by 50 percent with sanitizer-free water and then retest. Now a reading of 3 ppm is actually 6 ppm.

Along with free chlorine, this method can also test for combined chlorine, or chloramides. To get a sense of the free chlorine, simply perform the initial test for free chlorine and add a second reagent. The resulting color will indicate a total chlorine level. Subtract the previously ascertained free chlorine from the total chlorine level to get the level of combined chlorine.

OTO:
(ortholtolodine) This reagent has fallen out of favor in recent years due to its inability to distinguish free chlorine from total chlorine. However OTC, if properly used, can be just as accurate as a DPD test.

If the pool or spa you're testing is using bromine rather than chlorine, you can still test residuals using either OTO or DPD. Follow the same procedures you would when measuring chlorine and multiply the results by a factor of 2.25.

If you're measuring for chlorine residuals, you likely will be tracking your stabilizer levels as well. NSPI recommends levels between 30 and 50 ppm for cyanuric acid.

To test CYA levels, a reagent called melamine is used. The melomine will cause the water to become more or less cloudy (the aforementioned turbidigy test.) Low CYA will produce small particles that give the water a hazy appearance. Higher concentrations produce far more particles and turn the water very cloudy. The turbidity is then measured against a comparator chart depicting the relative visibility of a dot in the test vial, thereby indicating the corresponding CYA reading in parts per million.

The Acid and Base

Because chlorine only works effectively in certain pH ranges (low 7s or low 8s), it is just as important to monitor the water's pH level closely.

The reagent for testing pH is phenol red - or phenolsulfonephthalein. This is an organic dye that comes in both liquid and tablet form. In a small sample of water, one tablet or five drops are added. The resulting colors - yellow (low), red (middle) and purple (high) - will be accurate in a pH range of 6.8 to 8.4.

Two other reagents are also used in pH testing: bromythol blue, with a range of 6.0 -7.4, and cresol red, with a range of 7.2-8.8. However, phenol red remains the most popular because it closely reflects the pH levels recommended for swimming pools.

Again, be aware that a high sanitizer residual (more than 10 ppm for chlorine, 20 ppm for bromine) can create false pH readings. At these high levels, the sanitizer reacts with the phenol red that results in false colors. Many test kits n ow include a special neutralizing reagent that, when added prior to testing, ensures accurate results.

If your tests show you need to raise or lower the pH, another test will need to be done to determine exactly how much adjuster should be added. To lower pH, perform an acid demand test; to raise it, perform a base demand test.

The number of drops required to cause a color change in a water sample correlates to a chart that prescribes the amount of muriatic acid (to lower pH) or soda ash (to raise it) needed to move the pH in the direction you want.

Checking the Buffer

Total alkalinity (TA) is water's ability to neutralize acid, also known as the system's "pH buffer."

To test for total alkalinity, two reagents are required for your water sample. First, add the end-point indicator - a chemical that changes colors during the test. The second reagent, titrant, is an acid used to trigger the end-point reaction.

When the titrant is added and just exceeds the water's ability to neutralize it (it's an acid, remember), the endpoint indicator will suddenly change the water color.

This change in color happens fast, so it's important to pay attention. Count the number of drops needed to generate this end-point reaction.l The number of drops will determine the concentration of the water's total alkalinity.

It's important to perform this test carefully, test kit manufacturers say. To mix the titrant properly, the test vial should be gently swirled after each drop is added.

The Hard Test

Testing a swimming pool for calcium hardness is particularly important if you use calcium hypochlorite as your sanitizer, or if the source water is naturally high in calcium. Consequently, you should initially test both pool and water tap water and then test continually for 30 days. After that, remain current on the calcium hardness of the water.

Calcium hardness is measured using a titration method. The first step is to add a special pH buffer to the water sample. This will raise the PH of the sample to around 10 - the level at which the test is most accurate. Next, an organic dye is added that turns red when it reacts with calcium. Finally, add the titrant: EDTA, also known as ethyenediamine tetraacetic acid.

Add it one drop at a time. When the titrant has combined with all the calcium in the sample, it will turn the water blue. The number of drops required to turn the sample blue correlates to hardness in ppm.

Metal Health

While testing for factors such as chlorine and pH regularly makes sense, certain tests, such as the ones for metal, only need to be performed periodically, or if the service tech senses trouble and wants to perform a little diagnostic investigation.

There is always going to be some sort of metal in pool water, but if you feel it may be getting out of hand perhaps stains have already begun to appear - then performing a few metal tests would be in order.

Copper and iron are the two most likely culprits. Copper can find its way into your pools via copper-based algaecides and the corrosion of copper heat exchangers and heat sinks. Iron is usually introduced from source water -particularly well water.

If you suspect high metal content (as little as 1 ppm metal can cause straining), you need to invest in one of the various metal kits on the market.

Kits are typically colormatic tests that require two or more agents. Bicinchoninic acid is popular when testing for copper. It produces shades of purple in the water sample when that metal is present. The common reagent for detecting iron is phenatroline, which produces shades of orange and red.