Here is my current water chemistry, stable for about the last year:

FC 5-6 ppm
CC 0
TA 90-110
Ph 7.2-7.4
salt 3200
cya 40-45
cal 480-500

22,500 gallon inground, concrete, grey plaster, poolpilot swg, minimax heater, pentair 1.5 hp for pool, 2.0 hp for spa jets. DG filter.

I have been getting decent calcium deposits on spa spillway tile for the last few years. I have always assumed it was the high cal level. My fill water is 200-220...pool is about 2 years old. Entertaining significant drain and refill currently.

I covered the pool once it dipped below 80 in late october. I also wanted to see if sunlight on a covered pool would eat up less chlorine that the uncovered pool, and if so, how much. Well, I turned off the SWG and added a .75g of ultra bleach in early october, and I didn't have to add anything until this weekend (FC dipped from 6.0 to 4.0). I figured $1 of chlorine for close to 2 months of operation was a good deal.

But then I took a look at the spa spillway. Virtually no calcium deposits were present. i had cleaned them off back when I covered the pool, but haven't done anything to them since. Typically, there would be a fair amount (4-6 quarter sized deposits) within 2 months...but virtually nothing.

Has anyone heard of anything, scientific or anecdotal, about worsening calcium deposits by using an SWG (or the reverse)?

And for those who will tell me to drain and refill, I know. I am thinking about it. New pool...many have warned me to wait for the plaster to get a few years of cure on it before you drain.