I just started using the TFP method this year...when I started the pool up I was unable to get a FC reading and the CYA level was 0. Actually every time I open the pool the CYA is at 0. Chem Geek surmised that I had some bacteria and/or algae that grew over the winter and reduced the CYA. I solved this problem by slamming and have had no issues this summer....but here's where it gets interesting....
The Taylor test kit I bought had very little CYA reagent in it so I ran out at least a month ago. (We go away a lot and I travel during the week so there is no way I can not use Chlor tabs.) Since Leslies uses the Taylor CYA test I figured I would just have them do that test only until I ordered more reagent in the spring. For the last 6 weeks they have told me that my CYA level was at 30. I had a bit of an algae bloom a week ago even with the FrChl at 7.0!
I ordered new reagents early and tested myself for CYA. I'm a 100. Took it to Leslies, they confirmed 100 (different kid). I mixed 1/2 pool water and 1/2 tap water to make sure that the level wasn't higher than 100, and it is not.
I know everyone says that CYA stays in the pool all winter, but that has never been the case for me. So I'm wondering if I can close with the CYA this high assuming it will drop over the winter. My concern is that if something grows again it will have more CYA to consume and a bigger mess for me next summer. I'm going to wait till next week to close because here in jersey it will by 85 degrees for the next few days and I don't want to cover it when its that warm.
Thoughts? anyone else loose their CYA over the winter? My plan was to keep the FrChl at about a 10, Add some Polyquat, and close.