Why isn't my CYA increasing?

[yardoasis]

Two weeks ago, my CYA was about 25. I wanted to bring it up to over 40, so I switched to trichlor temporarily.

I've used up about 4 lbs of pucks in the past 2 weeks, but my CYA level is only 30. According to pool math, it should have went up by 22 to about 47.

Is there a reason why my CYA isn't going up as expected?

 

[JasonLion]

The CYA test is about +-15, so your CYA might have actually changed by 22, but you can't always see that in the test results.

 

[yardoasis]

+/- 15 seems like a lot, I tested 3 times and I got ~30 every time.

Is the heat and lots of sun light a factor in the pool using up CYA, given I live in a hot climate?

 

[JasonLion]

High water temperatures will have a small effect, but only something like losing 2-4 ppm/month.

Is there any chance you have a slow leak?

 

[yardoasis]

Is there any chance you have a slow leak?

Actually, yes there's a very slow leak... after I opened my Hayward to wash the the filters, I couldn't close it tight enough so there's a slow drip coming out from where the lid is bolted. After trying to screw it on tight enough, I shrugged it off figuring water is relatively cheap and I can always top off once a week. I see a small puddle of water just below the drip from the bolts.

 

[JasonLion]

That doesn't sound like enough of a leak to cause CYA to go down significantly.

 

[yardoasis]

Hmm. Weird. I don' t have auto-fill, so I'm pretty sure I don't have any other leaks. Besides my CH has been nothing but consistent, +/- 25 ppm.

Maybe the CYA in my trichlor isn't as strong as poolmath is saying? I've been seeing other threads lately from members having issues with adding CYA to their pools, testing little or no CYA after their additions... maybe something is going on, and we just don't know about it?

Other test results if it helps:

FC 11.5
CC 0
pH 7.6
TA 75
CH 275
No borates no salt
CSI = 0.03 as of today

 

[timerguy]

So, you've added 4 lbs that's about 8 pucks. Looks like it could have added 21ppm (or less, pucks aren't all exactly 8 ozs I had some that were more like 7 ozs), but like Jason said the test accuracy is+-15ppm so it could have been as low as 10 to begin with.