Starting with fresh water, I brought my pool up to about 40ppm CYA for a couple of years. After having read about the potential "shielding" effects, I raised my CYA level to 80-90ppm and did, indeed, see a reduction in loss of chlorine due to sunlight. I realize that can't help much with a shallow pool, but my anecdotal evidence seems to support the notion of shielding chlorine at deeper depths...,.

Thanks for a heads-up on the better options for phosphate removal.

Its great to see your posts again, Richard....