I have an outdoor above ground style vinyl pool located inside of a greenhouse structure. The greenhouse roof is 6 mil poly with UV stabilizer in it. The ends are screened with black nylon window screen, the ease end very treed and the west end near the house. This results in very little direct sunlight ever actually reaching the pool.
Under normal conditions the chlorine level changes very slowly. You can be out all day and not need sunscreen.
Under these conditions is CYA actually needed? If so, what level should I shoot for?