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Testing Your Pool Water

Chemistry Made Easy

OK, I’ll be the first to admit that I’m not into chemistry! I do however admire people who understand it. I love having conversations with them because they have a passion about chemistry that has always impressed me.

While servicing pools, my eyes have opened about some aspects of chemistry, but the fact remains, it’s not something that inspires me. As I was preparing to write this tutorial, I did extensive research using pool related books, magazines and manuals. I also talked extensively with industry professionals. After all was said and done, I came away a bit confused and decided that as I write this guide, I will keep it simple and easy to understand.

My belief is that when the average pool owner begins to read overly complicated manuals, they only get confused, frustrated and then lose interest in servicing their pool. My goal is to keep it simple.

Testing your pool water

There are four ways to test the water in your pool:

Testing Kits

  1. DPD Testing Kit can be bought at any pool store and use liquid reagent solutions in small bottles that come with it. They are very easy to use and involve nothing more than counting drops or comparing colors. Taylor Technologies makes one of the most popular kits on the market and I use their products extensively. The reality is, if you want to do it right, plan on spending around $50.00 for a professional kit. Beware of inexpensive kits not made in this country as they are far from reliable.
  2. OTO Testing Kit contains the same tests as the DPD kit except chlorine is measured by an older style of chemistry that turns yellow instead of the pink created with DPD. For numerous reasons, I believe the DPD system is a more reliable method as it measures the amount of active chlorine that’s available to kill germs. OTO cannot differentiate between active and spent sanitizer (chlorine).

    Important: You should always handle and store reagent solutions with care. Be sure to use the stopper that seals the testing container when it is shaken (but not stirred). WHAT NOT TO DO: Some people drop reagents directly into the pool and judge the quantity of chlorine to add by the flash of color seen in the water. This is not accurate by any means.
  3. Test Strips This is an easy way to test your pool water simply by dipping a small strip of plastic with colored squares into your water and measuring the colors against a chart on the bottle the strips come in. The disadvantage of test strips is that the more they are exposed to air, humidity and heat, the less accurate the reading. The solution is to use high quality test strips and store them inside at room temperature. If you remove a strip from the bottle, reseal it quickly.
  4. Electronic Reading - Advanced Photometers To me, this is one of the best, and most accurate ways to read your water levels. Simply by putting a small amount of water into a hand-held battery operated device, you get an exact reading at the touch of a button. As it is waterproof, you don’t have to worry about dropping it into the pool.

NOTE I: In my research, I have discovered an American company, Industrial Test Systems, that manufacturer’s high quality test strips and advanced photometers. I have done extensive research and comparison tests using these products with consistent success.

What’s The Right Water Testing Method For You?

When I first began writing, my vision was always to keep the chemistry chapter simple. Yes, there are over 16 ways to test pool water, but I have found that the main three; DPD Liquid Testing, Photometers, and Test Strips, work fine for the average pool owner. Are you looking for the intricacies of chemical testing and want to apply science and theory? If so, this guide may not be for you. However, if you want to understand the basics of testing water and will be satisfied with a cleaner, happier pool; this chapter will be right up your alley!

DPD Liquid Testing - As I have used the DPD liquid system on a daily basis for a number of years, I know it is reliable. However, you need to hold the dropper bottles vertically when dispensing reagents to guarantee that every drop you add is exactly the same. The liquids can go bad if exposed to air or heat. Both translate into unreliable results.

Test Strips - Over the years, I researched test strips with a variety of results. Some of the downfalls included: • Strips made outside of U.S. have low reliability. • Leaving the cap off the bottle, and storing outside, affects the strip reading. • Strip colors don’t match up to the color chart on the bottle.

PoolCheck™ Test Strips from Industrial Test Systems, Inc. (ITS) Upon extensive research, I found these to be the best on the market! What most impressed me is that when the labels are being printed, ITS representatives are always on hand to check that the test colors match exactly. If a color varies too much, the labels are thrown out. Also, the strips are not as sensitive to heat and contain only 1/100th of reagent chemicals compared to liquid test kits.

Combining sensitivity with safety  is what makes some of their products unique is the patented aperture (window) technology which allows pool water to pass back-and-forth through the test strips. This process gives extremely accurate readings and much greater sensitivity. In fact, this is the only test strip method (for free chlorine) which has been accepted by the U.S. Environmental Protection Agency (2007 Federal Register Vol. 72, No. 47, Monday March 12 p.11204, ITS method D99-003).

Testing Procedure - Simply dip the strip into the water with back and forth motion, remove and shake off excess
water. Then match the color to the label on the bottle.

Pool Check™ has a number of testing strips to choose from:

  • 6 in 1 tests: Free Chlorine, Total Chlorine, pH, Total Alkalinity, Total Hardness, Cyanuric Acid
  • 3 in 1 tests: Chlorine, pH and Alkalinity
  • 5 in 1 tests: Free Chlorine, Total Chlorine, pH, Total Alkalinity, Total Hardness
  • Salt tests: Salt levels for salt water pool

ELECTRONIC PHOTOMETERS (eXact® EZ Advanced Photometers) This test system impressed me the most! For those who desire 99% accuracy while removing any doubt in their mind about pool chemistry, this is the product for you! I have used other test meters in the past with fair results, but it was a bit involved and not all that convenient. The eXact ® EZ Photometer (fo-tom-iter) has the competition beat! The meter is waterproof (IP-67), uses AAA batteries, and gives you an LCD reading of your individual chemical balance parameters. The process is simple:

Remove the particular eXact® strip from the bottle, turn meter on, select desired test and activate. Fill meter with water sample and set at zero. Dip the strip - which releases the reagent into your water sample - and read the results which are displayed on the LCD screen of the meter.

The eXact® EZ test kit comes in a sturdy plastic carrying case. Each kit contains 4 bottles of different test strips: DPD- 1 (Free Chorine/ Bromine) • DPD-3 (Total Chlorine) • pH - (pH test) • and a liquid reagent to test Cyanuric
Acid. eXact® strips for Total Alkalinity and Calcium hardness can be purchased separately. The manufacturers have eXact® strips and reagents available to test 21 water quality parameters.

Admittedly, this is an investment priced higher than some options. However, if you look at it from a long-term perspective, this system eliminates the hassle and liability of matching colors and will give you accurate water level readings for many years to come.

11 Tips For Getting Accurate Results From Test Strips

  1. Read the instructions before using; each manufacturer has unique instructions plus a manufacturer’s may change over time
  2. Keep strips dry before use - wet fingers can spoil a whole bottle of strips
  3. Limit exposure to air and humidity by keeping the container closed when not in use
  4. Don’t touch the unreacted pads or put the pads in contact with anything else that might contaminate them
  5. Expose pads to water exactly as directed - dipping, swirling, and swishing are different motions.
  6. Don’t flick off extra water unless so instructed
  7. Let correct amount of time elapse for starting and completing the readings
  8. Read test values in the order given
  9. Prevent reagents running between pads by holding strip horizontal to the ground when comparing colors
  10. Make color matches in natural light without sunglasses
  11. Don’t use strips past the expiration date

The Centers For Disease Control (CDC) recommend people who use public pools and spas, like at the gym or a hotel when traveling, use test strips to test the water themselves before entering, just in case the operator has been negligent in keeping up with the sanitizer demand. For this reason, Taylor Technologies offers 10 test strips in a resealable foil pouch that fits into a pocket, purse, or gym bag.

Taylor Test Kits

The kit I personally have used the most is Taylor Technologies’ Complete™ Kit. People in the business often refer to it by the product number: the “K-2005” or “the 2005 kit.” Professionals favor this kit because it has an accurate all-liquid DPD test for determining the level of active chlorine (versus spent chlorine) in the water, and because it has all the tests for water balance. The 2005 kit includes a 64-page chemistry guide and a nifty round slide rule called Watergram® that tells you, after you plug in your test results, whether your water should be treated to address scaling or corrosive conditions that can damage pool surfaces and equipment. The K-2005 has been on the market for 40+
years and has an excellent track record.

About 15 years ago Taylor came out with a variation on the K-2005 called the “K-2006” or Complete™ FAS-DPD kit. The only difference is the chlorine test, which employs a powder reagent plus the dropper bottles with liquids. Instead of matching colors to get a reading, with this method you simply count the number of drops needed to make the
treated sample go colorless. Colorblind people can use this test successfully. The range of the chlorine test is greater too. It can read as low as 0.2 parts per million (ppm) and up to 20 ppm without the indicator color getting bleached out by a high level of chlorine. Although this kit is mostly used by health department inspectors and public pool operators, I’ve met homeowners who really, really like the K-2006. They are either very techie or they’re among the 6-8%
of men (and some women) who can’t match the pink colors of the standard DPD test.

Most recently, Taylor introduced a test kit that does for residential pool owners what the K-2005 does for industry professionals. Called the i-CARE Kit™, or “K-1005,” it’s priced lower partly because it doesn’t contain the Watergram
® or big chemistry guide. You go to Taylor’s online water analysis program to plug your test readings in and get treatment recommendations (the “i” in the name stands for Internet), or use the charts provided
in the kit. I’ve used the i-CARE kit and can recommend it heartily.

For those of you who are only interested in test strips, I should mention Taylor offers 4-way and 6-way strips in a unique shaker dispenser that prevents wet fingers from spoiling the contents. If you can’t find Taylor’s sureTRACK® strips in a store, they’re available on our company’s website,