CYA increasing on its own?

[Stacerp]

My CYA is at 90 today, maybe closer to 100. A few days ago at 70. The week before, 60. I haven’t added any stabilizer for a few weeks. I thought it would only increase with the addition of stabilizer? I’m using the Taylor DPD test kit. Have an above ground 10,000 gallon pool with an Intex 2150 GPH pump & SWG with glass media. Run the pump 24/7.
FC 7.5
CC 0
PH 7.8
TA 80
CH 200
Salt 3250
Temp 70° (at 8am, has been around 80° until 2 days ago)

 

[Brett S]

What are you using to chlorinate your pool? If you use tablets (which are likely trichlor) then that will add CYA to your water. If you use granular shock then that could be trichlor as well and that will also add CYA.

 

[mknauss]

Welcome to the forum!
How are you chlorinating your pool water?
I suggest you read ABC's of Pool Water Chemistry.

 

[Stacerp]

It’s a SWG. Intex 2150 GPH pump & SWG with glass media. Run the pump 24/7. I’ve never shocked it. The only thing I’ve ever added has been the salt, of course, stabilizer, and 31.45% muriatic acid (5 days ago and 19 days ago).

 

[mknauss]

Then there is a testing error.

How much stabilizer did you add? Since this a fresh fill, your CYA level can be calculated based on how much stabilizer you added and the volume of the pool.

 

[Stacerp]

I added 2 lbs Clorox dry Chlorine Stabilizer two months ago and the same a month ago, based on what this app suggested. Only time I’ve added it Should it be going up this many days later? What do you mean by fresh fill? Pool was first filled/opened the end of May. I have tested almost daily so I feel like I have a pretty good handle on the testing, but maybe I’m doing something wrong? I rinse the bottle a few times after each testing but maybe some residual is etching into the plastic & screwing up the results - could that be possible? Thanks for your help, by the way!

 

[Brett S]

Yeah, it does seem like it must be testing error. If this is new water and you have literally only added 4 pounds of stabilizer to it, then your CYA can’t be any higher than 48. (According to poolmath, 4 pounds of stabilizer in 10,000 gallons of water will raise CYA by 48). And I would expect it to even be slightly less than that, due to splash out and such.

 

[Chasarms]

The CYA test is my nemesis.

 

[Mdragger88]

How did u add the stabilizer? Sock method or directly to skimmer?
what are the dimensions of your pool? Could your water volume be over estimated?

 

[Stacerp]

How did u add the stabilizer? Sock method or directly to skimmer?
what are the dimensions of your pool? Could your water volume be over estimated?

Actually, I have it as 8,638 gallons in the app settings (so that would not change the app’s recommendation). It’s round, 20’ x 52”. Yes, I used the sock method.

 

[Mdragger88]

It changes the 4lb addition from 48 to about 55. On a fresh fill . Meaning u had no cya to begin with.
be sure to to do the test in full sun w/your back to the sun. I also pour the mixture back in the little squirt bottle & read it again( I do this several times) & kinda average the results.
Try not to stare at the dot - fill to 30 then glance, 40 - glance etc

 

[middleseat]

Good idea on the CYA test, Mdragger88. I never thought of pouring the solution in the test tube back into the squirt bottle!

The CYA test is my nemesis too.

 

[Jeff J.]

Good idea on the CYA test, Mdragger88. I never thought of pouring the solution in the test tube back into the squirt bottle!

The CYA test is my nemesis too.

You could order the 50 CYA Standard Solution from tftestkits.net to see if you're reading it right.