Accurate Pool Water Testing

I got an email the other day from a customer. "I hadmultiply the number of drops by a certain factor,
a local guy with a computer who did my waterusually 10, to determine the reading, in ppm (parts
tests... It was great... I got a print-out report everyper million).
week with suggestions by chemical. WorkedReagent test kits range from $5 "Duo" Test kits,
perfectly and my water was like glass. They are nowhich only test for pH and Chlorine, to the pool
longer in business and everywhere else uses a 19management standard K-2005 test kit (shown), to
year old kid with test strips... the accuracy dependingthe Professional Field Lab test kit. The fancier test
on a) how much he had to drink last night and b)kits will have Comparator Slides, which are color
whether he really G.A.S. that day. Can I buy my ownimpregnated glass slides that won't fade or glare in
computer (?) for under $1K?"the sunlight.
My reply showed my slight distrust of the printout.Digital Test Kits
"Some of the software that operates these storeFor the ultimate in accuracy, and the testing method
testing 'printouts' are designed to sell more chemicals."chosen by our customer mentioned at the start of
I explained. Then we got into the discussion ofthis post, take a look at the ColorQ test kits by
accuracy. More than a printout (which I later had toLamotte. ColorQ test kits eliminate the need to
admit was rather convenient), what was mostvisually determine slight color variations or use look-up
important for our customer was having accuratetables, thus taking the guesswork out of poolside
measurements of his water balance, and an easywater analysis.
way to know what chemicals, if any, he needs toPopular with health departments, municipal pools and
add to the pool.YMCA's - they give highly accurate results and are
Test Stripsvery simple to use. An internal photometer measures
The least accurate method of testing your poolthe sample and provides the user with the next
water. Test strips are also the cheapest, simplest andsteps, or what to add to the pool. Still no printout,
quickest way to test your pool water. Just dip thebut you could keep a log if you wanted to.
strip in the pool water, swirling for about 30 secondsAnother popular digital Test kit is the Scuba+
and then compare the colors on the test strip to theelectronic tester. Drop in a tablet, swirl under water
colors on the bottle. "Comparison" tests such as this(the Scuba+ is an immersible tester) and the
rely on the user to match the color and are subjectphotometric reader does its work. Displays to the
to mis-interpretation or educated guessing.user the measurement on the LCD. This item is
A more accurate Test Strip came to market a fewpopular with pool guys, fits in a pocket of your cargo
years back. Digital strip readers take the guessworkshorts.
out of reading a test strip. You still dip and swirl, butWith test kits, the axiom holds true, you get what
then insert the strip into the handheld TruTest Digitalyou pay for. If you want accuracy, you'll need to pay
Test Strip reader and it will give you a digital read-outa few more dollars. For the average pool owner
of your test results.however, I would recommend the $50 K-2005 kit.
Reagent Test KitsThis will test all of the parameters important to
The next most accurate way to test your water.water balance.
For Chlorine testing, there are OTO and DPDOne more thing...there are some water testing
methods of testing. OTO is the yellow colored testtechniques or tips that will also help improve accuracy.
result. It computes Free Available Chlorine but does
not test for Total Chlorine, which means that you1. Always use Fresh Reagents, most have a shelf life
cannot compute the level of Combined Chlorine inof 1 year.
your pool. DPD is more accurate.2. Store reagents in a cool, dry location, out of direct
Test kits use reagents that you add, drop by drop,sunlight.
to your water sample. Chlorine and pH tests are a3. Take your water sample from under the surface.
Comparison test, which means that we are relying onTesting surface water may yield inaccurate results.
the eye of the tester to make an accurate color4. Keep your testing vials clean and rinse well
comparison. Total Alkalinity and Calcium Hardness andbetween tests.
Cyanuric Acid (Stabilizer) tests are "Titration Tests",5. If you get an odd test result, test again to be sure
which means that we count the number of dropsbefore adjustment.
added until we observe a color change. Then we