I am trying to close my pool and have been doing on OCLT for a week now. CYA=60 slam FC=24, yes? Ph=7.4, water is crystal clear. Yet, I have an overnight loss of 4-5ppm. I did 3 days of slam, vacuuming, backwashing, and each morning a 4-5ppm loss. I decided its getting cold, today was down to 28 degrees, and to stop the slam/oclt and see where FC stablized. Currently have had FC=11 for 48h without any loss. My question is: IF there is algee in the pool how is it that there is no OCL at 11, but at 24 there is? What am I doing wrong? Is it safe to close the pool if I get FC back to 24 and then just cover the pool?
TIA
TIA