Check out some similar questions!

johnmt · Sep 24, 2008, 02:31 AM

How can you clean the sides of an inground pool

albinfla · Sep 24, 2008, 05:04 PM

What type of pool, and what type of staining?

johnmt · Sep 25, 2008, 02:34 AM

It is a fibre glass pool and the stains appear to be water stains (brown)

albinfla · Sep 25, 2008, 09:01 AM

John,
The good thing is that a fiberglass pool is much easier to remove stains from.

The stain is probably mineral stains, either iron, or manganese.

To remove, you first need to check your ph, alk, chlorine. PH should be in the 7.0-7.8 range. Alkalinity needs to be 90-120, chlorine 1.0-3.0. For this application, the chlorine can be lower than 1.0, but should not be higher than 3.0. The ph and alk are critical for this application.

If the ph, and alk are good, use a hard water mineral stain remover. You can pour it along the walls, or even better, apply through a garden pump sprayer directly to the spots.

They will probably go away within a day.

One other possibility is black algae stains. Those would be removed with algaecide. If you have kept on top of chlorine, and routinely shock treat, that is probably not the issue.
Al

ballengerb1 · Sep 25, 2008, 05:14 PM

We recently heard in the plumbing section that fume free oven cleaner works wonders on fiberglass. After using the oven cleaner I am wondering who started this unfounded rumor, probably Easy Off.

albinfla · Sep 25, 2008, 07:17 PM

You would think it would eat the finish off. I have used boat products. But, that doesn't work under water. Putting that mineral deposit remover in a garden sprayer really bailed me out on a commercial pool earlier this year.

The owner let the pool go to pot over the winter, and called us to re-work the pump house, and to help them get the pool in shape. They had heavy pods of blue-green algae all over the pool. And, they had iron/manganese staining from their well water. We rigged up an ozone sprayer to hit the spots with. That killed the blue-green algae. Then, we sprayed the mineral deposit remover on the spots and it did a real good job. The PH and alk have to be right though. I had a customer that turned his entire pool water brown for a few days by using it with low ph.

I guess Easy Off would work if there was a lot of oily build up from body oils, and suntan oils.
Al