Low calcium levels, plasticizers in vinyl liners, leaching cobalt from fibergalss?

[CarlD]

Dave reminded me: Etching in the dishwasher not only takes place at high pressure, but at very high temperature as well and that usually makes most chemicals more reactive.

[waterbear]

I just found some info on the San Juan Fiberglass pool website that is interesting concerning this topic. I own a San Juan Cocoa Beach model. Their maintenance manual (downloadable from their website) states:
"Calcium Hardness (C.H.) is the relative hardness of your pool water, and is measured in P.P.M. If the water is too soft, it will be aggressive and erode pool equipment such as heaters, ladders and even the gel coat finish. If the water is too hard, deposits will form on the pool equipment and finish. 300 to 350 P.P.M. is the proper hardness for your San Juan Pool and should be checked monthly."
One of the largest manufactuers of fiberglass pools recommends CH levels of 300 to 350 ppm to help protect the gelcoat if I read that properly. The maintenance manual also recommends ALK between 70-80 ppm. I am going to check the other major fiberglass manufacturer's sites to see if they say anything similar.
Edit: Just checked Royal Fiberglass pools and downloaded their care manual. It recommends CH between 200-400 ppm and states that low Ch levels can cause "Distorsion of pool finish" and "Premature aging and shorter life expectancy of the gelcoat finish"