Hi Richard.
I love your deep studies of the chemistry in our pools. Having an understanding of the “why” seats the information much more permanently than memorizing the charts. Keep them coming.
Last fall I drained 6480 gallons out and refilled with well water to bring the CYA level from 45 to 30. I stabilized the chemistry in the pool (based on Ben’s BG Chart) for the winter (without shocking) to the following:
FCL 4.5 -- range 2.2 – 5.1
TA 70
PH 7.5
CYA 30 -- Range 25-35 --- NOT a SWG pool
The pool is covered with a mesh Loop Loc cover which allows the rain and fine dirt to pass through (keeps the big lumps out).
Since the winter (so far) has been very mild, I have been throwing the Aquabot in once a week and checking the chemistry. So far, the FCL has dropped very slowly, and I have made 1 adjustment (Less than a gallon of 6% bleach) since November to keep in my range.
I keep accurate rainfall records so I will know how much dilution from rain/overflow and will be able to predict fairly accurately what the CYA should be in the spring when I reopen the pool. If it is significantly different from the predicted level I will know that your theories have come into play.
Once again --- Thanks for sharing your knowledge, I’ll keep you posted.
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