Unreliable Store Water Test?

sbe

Active member
Sep 4, 2008
39
I've been testing at home and at the same store for over ten years. The tests have always pretty much matched but today their test indicated Cyanuric Acid at 38 ppm and I run my pool without any CY, never have. I know that's strange but it works for me. What I'm wondering is how a supposedly professional grade tester could be this wrong or what else could explain this?

Any ideas?
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
18,211
Bedford, TX
sbe

How do you put chlorine in your pool?? Have you added any "Shock"???

A pool without any CYA makes the chlorine very harsh.. I don't know how you can stand it... :scratch:

We never trust pool store tests.. That is not to say that some of them don't do a great job, but there is no way for us to tell.. As a general rule, if you take the same water to 3 different pool stores, you will get three different answers.. Small mom and pop pool stores do better than the well known chains, as the chains have a huge employee turnover rate.

Thanks,

Jim R.
 

sbe

Active member
Sep 4, 2008
39
I live in Portland, OR where we'll get a 90 degree hot day like today, then the temperature plummets to 60 for a few days or a week then maybe it gets hot again, or not. That means pool use is sporadic and because I've got an automatic cover the pool its only open the few hours its when actually being used. That means its pretty easy to keep the chlorine level where I need it because the only time it gets UV is when we're swimming. Even then it's only a couple of people in a 25,000 gallon pool so the load isn't very high. The chlorine rapidly goes to zero of course when the cover is open but I re-chlorinate when where done, close the top and the level stays pretty good, perhaps with a bit of topping up, until the next time I open it up.

I know it's odd but no CYA makes it easy to super chlorinate although we've never had to. No problems in more than 10 years. But when you only have 4-6 people using a pool and it's only for a couple of hours for a couple of days per month and the pool is constantly being cleaned with a pool robot there isn't much to get rid of.

I use liquid chlorine. Nothing else other than whatever I need to balance the pH and adjust Total Alkalinity and Calcium Hardness.

Good to know it's probably the test. Still showing 38 ppm when the real number is zero makes the test entirely useless. Weird, especially since every other time they've tested it's shown the correct number...zero.
 

sbe

Active member
Sep 4, 2008
39
Sorry I forgot to ask. We have no chlorine smell and the combined chlorine always read essentially zero. What do you mean by harsh?