Bouncing CYA levels

[flipr]

Did a search and found that CYA will not typically move except by dilution, or draining water.

I test weekly, and have been chasing Chlorine too, even with SWG, so starting SLAM. But I've used 7# of CYA in last 2 months. Its been a weekly add. We've had some rain, a couple heavy storms, but not to where we have had to drain pool. Rain gauge says less than half inch in the last 2 weeks.,

Our poolmath is set with goal of 70 CYA.

Weekly readings in June have been

6/4 40, added per PM
6/12 30, added per PM
6/18 30 added per PM

6/26 50 added per PM
Full test from yesterday
FC 2.5 (my testing tube is collecting black residue on the bottom?
CC 0
PH 7.4
Alk 90, added acid to 7 and will aerate to bring ph back up.
CH 420
salt 3400

I know CH is over my desired, holding off doing the drain until I kill off whatever is consuming FC

I'm using granular CYA, putting in sock in skimmer. That is empty in a day. Have not cleaned filter weekly, as the pressure gauge didn't require it, but cleaning monthly. Been adding supplemental 10% chlorine as well, for what Pool math recommends for our desired 70 ppm CYA.
SWG isn't keeping up, been hot and sunny, but running 8 hours at 100% daily isn't keeping FC where I want it.

Your thoughts on the CYA usage?

TIA

 

[JohnT]

The most likely cause of that would be a leak. Do you have an autofill?

 

[flipr]

The most likely cause of that would be a leak. Do you have an autofill?

No sir, just rain and a hose. Have not had to add water for a few weeks.

 

[jblizzle]

I too was suspecting a leak ...

Are you always using the same brand of CYA? Maybe you got a bad batch that is not actually raising the CYA as it should?

Volume set correctly in PoolMath?

 

[flipr]

Thanks JB, no way of knowing if CYA was a bad batch, bought from Amazon, Pool Mate brand. Local pool store had a sale running this past weekend, so I bought some of theirs for same price this time. Will see with next go-round. Suncoast I think it was? Thanks for the info, will keep taking readings.