Sources of Metal

[grangerhj]

I was having the same staining problem with my fiberglas pool this year. I found that keeping my pH between 7.2 and 7.5 and my chlorine at about 3ppm kept the stain away. If my pH creeps up the stain returns- Can't explain why.

[mbar]

grangerhj is right, you must keep your ph on the low side in a fiberglass pool. Fiberglass tends to stain very easily. Metals can get in your water in so many ways. Even calcium is a metal. If you have been using Proteams metal magic, you probably have a lot of sequestereing agent in the water, so taking your ph down should eliminate the stains. Also keep your alkalinity about 80, and your calcium low - about 150. Keep your chlorine on the low side of your "best guess chart" and use bleach instead of pucks or calhypo.