hmmmm, trying to get the cya right

[pepsiholic]

When I opened my pool last week, I scrubbed it up, schocked and balanced everything. My cya was reading really low for some reason (20 or less), so I added enough stabalizer to get it to around 40-45, didn't want to overshoot. I was out of reagent, so I went ahead and ordered more. Over the course of this week, when I tested the chlorine levels, I noticed they were not holding at all during the day. I saw no visible algea, but decided to shock yesterday and last night. The chlorine levels held overnight. I went ahead and tested my cya again, even though it hasn't been quite a week yet (5 days close enough, right?) My reading was still only around 20-25, so I just added enough to get it back up to 40-45. I guess my question is, was it too soon to add more? I was going through the bleach like crazy just to keep the chlorine at a safe swimming level. I really don't know where it went, but I have read on here that sometimes it just disappears.

Here are the rest of my numbers:
FC 16 (from shock last night)
CC 0
ph 7.5
TA 100
CYA 25 or so

 

[Suziqzer]

Did you do any backwashing after you made the first addition of CYA?

 

[pepsiholic]

I think I may have. There was a lot of dusty sediment laying on the bottom, and I vacuumed it all up. I hang my cya from a nylon and let it disperse, so I didn't think backwashing would be an issue, but maybe. Thanks. Otherwise, my water is crystal clear and sparkling, so I guess I'll just wait it out until next week to see if it registers.

 

[madwil]

also, the CYA test is +- 15, I think; so reading 25 could really be 40...