I checked my CYA at closing in early October and it was sitting about 45-50. I SLAM'd for a couple days, winterized, and closed the cover. This year has been cold and rainy, so the pool hasn't been opened since October. I opened it on Saturday and it looked pretty bad. Lots of earthworms and debris, and the water was pretty cloudy. No problem, been here before. I measured FC and PH - 0 and 7.4. I started up the pump, put DE in, and let it run. Like a moron I didn't check CYA.
I brought the FC up to SLAM level and by the end of the afternoon, the water was clearing up. Checked again and it had dropped from 18PPM to 12PPM within about 3 hours - YIKES!. I added more, closed the cover and called it a day. Sunday I checked in the morning, and FC was down to 8PPM. I added enough to bring it back up to 18. Checked again, back to 12. That's how things have been since Saturday. It dawned on me this morning that CYA might be off. Sure enough, it won't even register on the test.
Is it possible for CYA to drop from ~45 to undetectable over the winter? If I just bring it back up, should FC hold or is there something else going on?
I brought the FC up to SLAM level and by the end of the afternoon, the water was clearing up. Checked again and it had dropped from 18PPM to 12PPM within about 3 hours - YIKES!. I added more, closed the cover and called it a day. Sunday I checked in the morning, and FC was down to 8PPM. I added enough to bring it back up to 18. Checked again, back to 12. That's how things have been since Saturday. It dawned on me this morning that CYA might be off. Sure enough, it won't even register on the test.
Is it possible for CYA to drop from ~45 to undetectable over the winter? If I just bring it back up, should FC hold or is there something else going on?