CYA will not increase at all... really confused.

[ChatWithaNinja]

Hey pool braintrust!
I got the house and pool in July and since then its been great. I've been trying to raise the CYA for the past 2 weeks though with NO results.
the previous owner left me a large container of Cyaneric Acid. I've probably added 120 volume ounces to the 40,000 gallon pool and CYA is still registering 0.
CYA is supposed to be the first step to a long term healthy pool... so now I'm starting to get worried... hahaha.
It's a vinyl pool. 40,000 gallons. PH is right at 7.4-7.6. FC is wildly fluctuating because CYA is 0.
I've been maintaining it by dropping a gallon of concentrated bleach (walmart 8.25% I think) every other night. Pool has been clear for over a month now as long with occasional slight (very slight and only because I am looking for it) greenish hue if I skip bleach night.

My long term plan is to keep the pool open year round if I can while covering it for the fall months because of the overhanging trees from the neighbors yard.

EDIT: bad math. 120 ounces, not 240. a cup is 8 OZ not 16... der...

 

[PAGirl]

What brand was it you used? Reports have been that the HTH brand has not been performing as it should in some cases.

 

[Mike1162]

What are you using to check CYA?

 

[mgoblue]

What brand was it you used? Reports have been that the HTH brand has not been performing as it should in some cases.

I ran into this as well....trying some of my pucks to see if that helps raise it before going and buying another brand to try. I added 3/4 of a container of HTH over a few weeks this summer and didn't register....

 

[Agent99]

What brand was it you used? Reports have been that the HTH brand has not been performing as it should in some cases.

Well that is interesting. I bought HTH brand from Home Depot and dumped it into my freshly plastered and therefore filled-up pool. Measurements since then (over ~7 week period) put me around 30 ppm when I was expecting 40 ppm. Not a big deal but had me curious.

 

[Leebo]

Hey pool braintrust!I've probably added 120 volume ounces to the 40,000 gallon pool and CYA is still registering 0.
CYA is supposed to be the first step to a long term healthy pool... so now I'm starting to get worried... hahaha.

For starters, what are you using to test with? The 120oz added to a 40k gallon pool should only have raised the CYA to around 20, which is VERY hard to test for. Try to add another 60oz of CYA to the pool to see if you notice an increase.

Well that is interesting. I bought HTH brand from Home Depot and dumped it into my freshly plastered and therefore filled-up pool. Measurements since then (over ~7 week period) put me around 30 ppm when I was expecting 40 ppm. Not a big deal but had me curious.

A 10ppm difference in the CYA test is completely normal. There are multiple different factors that come into play that could explain this little of a difference, from the user reading the results incorrectly to the pool being larger than expected. This is the main reason we suggest "creping" up on a goal for your CYA rather than trying to reach it right off the back. It's VERY easy to overshoot your target.

 

[ChatWithaNinja]

I'm using Aquabrite Chlor-Sta - 100% CYA

I'm using the Taylor K-2006 test kit. The r-0013 was empty in the kit so I purchased 1 pt from Amazon and am using that refill in the squirt bottle.

Yes, 120oz will not raise me above 20ppm, but it should at least be a little cloudy with the taylor kit, right? I'm clear as clear can be on the test even if I fill the test part all the way to the brim.

I'm going to do a bucket test. fill a bucket with water from the pool and dissolve a cup of CYA in it and test it...

 

[DaninFLA]

the CYA test has a pretty big margin of error/accuracy, I believe around 10-15ppm. so really hard to determine lower results. if its not up to 30ppm, then add enough based on pool math to bump it up another 20ppm...wait a week, and then retest.

 

[ChatWithaNinja]

Good news!
So I did the bucket test. I dissolved a cup of chlor-sta in about 3 gallons of water and one drop was enough to "not see the dot" in the test kit. So test and chemical are both valid.
I went ahead and dissolved another 2 cups in the bucket and tossed it in the pool.
Today my CYA is up to @28!! Going to add more today to get it up to 40.
Thanks for the advice everyone. As usual, when I ask why its not working, it then works shortly afterwards...