The experience I have had is that when I first had my fiberglass pool, the pool company put in lots of calcium. When I switched from baquacil to chlorine, they put in mega doses of calcium, then shocked it with calhypo. I ended up with lime green water, then milky water, then a pool that was completely stained yellow. That's when I took control of my own pool, I found this forum, and have been happy ever since. Last year I ran my pool with calcium of 25, I had no problems. This year I bumped it up to 125, because of all I read about fiberglass leaching out if there is no calcium - it didn't make sense to me. I know that fiberglass has trouble with plating - but in my own experience, and my opinion, it is high ph along with high chlorine that brings on that situation. So far this year by running my pool with a good sequesterer, ph no higher than 7.4, and alkalinity on the low side - about 80, I have not had any staining problems. I have read on some sites that fiberglass pools will not be warranteed if there is not calcium of 300 in the water. My pool didn't come with that provision. I can understand that calcium is needed in a plaster pool, but I don't know why fiberglass would dissolve unless the water was acidic.
