Staining - yellowish on pool moulded steps

[Sol11]

I have a fibreglass swimming pool that is only 2 years old, over this period yellowish/browish staining has appeared on shell - more noticable on the the edges of all the steps/raised mouldings.

Has any one got a suggestion for removing these stains.

[dynamictiger]

Try adding a cup of acid directly on the stain when you need to adjust your pH. Fiberglass loves acid, and it can be quite effective in stain removal.

[tmcdaniel]

My water was clear, steps were white, etc. on Saturday. Our local pool store tested my water and had me add 50lbs sodium bicarb, a balance pack, and 3 bags of burn out shock over a few hours of time. On Sunday, I awoke to a huge mess. Everything in my pool that was white (fiberglass steps, skimmers, etc. were a yellowish brown stain. I tried scrubbing it off with no success. We took a water sample and pics to the pool place this morning and they sold us a bottle of Revive to treat the pool with. I sure hope this works.