brown stain on fiberglass pool

Stains on the pool surfaces, pool equipment
or on the swimmers, or off-color swimming pool
water. Discolored but clear pool water.

brown stain on fiberglass pool

Postby justden » Thu 29 Nov, 2007 19:35

I have a small inground/indoor fiberglass pool with a geothermal heater, I have owned the house for about 6 months, so I don't have to much history on the pool. I use bromine and I keep the pool temp at 90deg. The problem is a tan/brown stain on the fiberglass, which I have removed three times now with Stain Free and Metal Free, it works great but then the stain comes back. Does anyone have a permanent solution and or an idea what is causing it. I did add about 2000 gal. of well water three months ago but have done the stain free twice since then. Could it be copper from my heater, if so is there a fix? Do I just need to keep adding the SF and MF and washing out my filter and eventually it will stop comimg back. Any ideas?

Thanks in advance,

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Postby mr_clean » Fri 30 Nov, 2007 14:32

tan/brown stains are a sign of iron in the water so your heat pump is probably fine if it has copper heat exchange.

The only way to deal with the iron is by using the sequestering agent like you have been doing. This will allow it to remain in solution, thereby avoiding the risk of precipitation or discoloration. Some Mineral Treatment products use the term "remove" in a very general sense. They actually mean "helps control." So you will need to keep using or replace water from somewhere else.

I would think the well water you added has iron in it & you can take a sample of the well water & get it tested at a pool store so you know.

brown stain on fiberglass pool

Postby horse1 » Tue 12 Jul, 2011 16:35

I talked to the Blue Hawaiian distributor and he said it was from the heater breaking down and would always happen.
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Re: brown stain on fiberglass pool

Postby paulbest » Mon 08 Aug, 2016 22:56

A fiberglass swimming pool is comparatively easy to keep clean. Frequent testing can help you maintain the optimal water balance. It is important to have a pH balance below 7.2 to keep the water from stinging as you swim in it. The total alkalinity needs to be below 80 parts per million. Maintain your chlorine at or below 1 ppm and the calcium hardness at 200 to 400 ppm. If any of these numbers get out of line, stains can develop.

Replace your old swimming pool filter with one that filters metals. This helps to keep metallic elements from settling on the pool steps, walls and floors and causing stains.
Most fiberglass pools have a gel coat that protects the fiberglass. In most cases, you can simply clean the gel coat with tile cleaner. Avoid scratching the protective coating.
If you have stains you cannot remove, consider covering them with a decorative pool decal. You don’t have to drain the pool to apply the decals.

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