I have a salt water fiberglass pool with a SWG and an automatic cover. We only use the pool for about 4 times a week, about 3 hours each time, otherwise the cover is closed. Here are the numbers:
SWG setting: 20%
So far the only problem was metal stains which were cleaned up by ascorbic acid treatment. The water is always sparkling. I was wondering if there is a need to increase CYA since most of the time the pool is not exposed to sunlight. I don't want to increase FC too much as it may promote metal stains.