Test strips

Meaty

Well-known member
Sep 8, 2015
57
Dallas Texas
Hi
im completely new to pools so I will likely have many dumb questions. Our pool is getting installed in the next few months so I'm trying to learn how to properly maintain it. This forum has lots of great info I'm still working through but it seems test strips aren't mentioned/recommended.

they seem like a convienent way to test the water. Is there something I'm missing? Is there no test strip that is reliable?

thanks
 

pooldv

Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
Aug 10, 2012
25,408
FL panhandle
Welcome to TFP! Congrats on the new pool.

That is correct, test strips are very unreliable. They are actually worse than dipping your finger in the water, holding it up to the wind and saying the first number that pops into your head. Because you tend to think the test strip might be right and it probably isn't. At least you won't ever believe the first number that pops into your head! :)

There are really two good test kits that we recommend. The Taylor K-2006 and the TF100 from TFTestkits.net. I have used the TF100 for over 3 years. More here, Pool School - Test Kits Compared

Also, have you read this? Pool School - ABCs of Pool Water Chemistry
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
15,866
Tucson, AZ
The best test strips can do is give you a color to read. Color matching is imperfect at best and often the graduations on test strips are far too course to give you any ability to maintain water. For example, CYA test strips will often show values like - 0, 15, 30, 100, 150, "Too High". That level of precision is complete useless as the amount of FC needed to properly maintain your pool (i.e., the amount of bleach you add) is HUGELY different for each of those CYA values. Also, most test strip chemistry assumes that the various components of water chemistry are within a balanced set of values. However, if your FC is too high, then most of the test strips colors will be bleached out rendering the test strips useless.

So, this is why TFP uses the industry standards (Taylor Technologies reagents) for drop based testing. It is the only way to independently measure all water parameters with the precision necessary to make appropriate decisions about what chemicals you need to add to your water. The most expensive kit will cost you ~$100 but using it will save you hundreds of dollars per season on chemicals.
 

Meaty

Well-known member
Sep 8, 2015
57
Dallas Texas
Thanks. It seems the TFtest kits are the best bang for the buck. Where's the best place/site to buy one? How many tests does it do before having to buy another? It looks like you guys recommend testing daily, correct?
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
15,866
Tucson, AZ
Thanks. It seems the TFtest kits are the best bang for the buck. Where's the best place/site to buy one? How many tests does it do before having to buy another? It looks like you guys recommend testing daily, correct?
You only need to do daily testing in the beginning when you're figuring out the whole pool water chemistry maintenance process. Once you get the hang of it and understand your pool (all pools are different), then the only daily testing you will be doing is for chlorine and pH and that will only be during the hottest and heaviest pool use months. The other tests would be weekly or monthly.

If you buy the TF-100 with XL option and a SpeedStir, you will have more than enough reagents to last you a long time. My first K-2006 Kit (like the TF-100) lasted me 18 months before needing refills.


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chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
See this post that compares drop-based test kits to test strips. Even if test strips measured correctly, their visual resolution is low and most don't test Calcium Hardness (they test Total Hardness that includes Magnesium).

Technically, some of the tests such as FC and pH should be OK, but the FC test is sensitive to how you dip and move the strip since too much movement leads to dilution of the dye from the pad while removing the strip and having water sit on the pad can have inconsistent amounts of liquid. So technique becomes important and that's difficult to achieve. Then one must compare the pad color against a standard and that is also difficult, especially with pads where the exposure to chlorine may be uneven. Then there are effects of time exposure and temperature and CYA level that affect the rate of reaction of chlorine with the dye in the pad. These issues don't occur with drop-based kits, in particular with the FAS-DPD chlorine test that is a titration (count the drops) test. If FC pads are exposed in a consistent way and read colorimetrically, then they can produce reasonable results, but that's not how manual test dip-and-remove strips are exposed nor measured. The DPD tests are also limited in how high they can measure FC, usually only to 10 ppm because high FC bleaches out the DPD dye.

The TA test is even more challenging for test strips since it attempts to measure pH changes with acid addition from the pad, but again is sensitive to technique. The CYA test is the worst since it works by seeing the pH change when melamine reacts with CYA and this depends on the starting pH and the TA level.

Even the pH test that should be the easiest for test strips to do can be a problem on some strips because they don't have the proper mix of chlorine neutralizers so they won't read the pH correctly with even modest chlorine levels. Taylor takes great care to have a proprietary blend of chlorine neutralizers that themselves (in combination) do not significantly affect the pH when chlorine is neutralized.