What is the best way to clean stained fiberglass simming pool steps?

Assuming its just algae based stain, any pool brush should work fine, and use an algaecide as part of your normal pool maintenance.

If it's a metal stain (and if the area isn't too large), Vitamin C should work well. Take a good number of tablets in a sock and scrub the stained area. If this removes it, it is likely a metal stain. And by using the sock, you can do it without lowering the water (use a white sock for this). Ascorbic acid is sold at pool supply stores for this purpose, but it is a powder form and it's expensive (over $30 normally for a two-pound container. Plus it will take longer the work that way. But that is the way to go if it is a large area of the pool.) I'd also recommend having the water checked for metals and use a metal remover if present. (The ascorbic acid normally has this in it's directions...)

How To Clean Pool Steps

Normal algae build up will come off with brushing after shocking the pool. I suspect you have metal stains on your stairs. Go to your local pool supply and get you some chemicals that get the metal out. After treating the entire pool's water, the stains will brush off easily.

i got here across a trick to this. it is going to stink for a lil bit yet won't final long. Get a sprig bottle or squirt bottle. Fill it halfway complete with warm or heat water and pour a lil bleach in it. Shake it up and in basic terms spray it everywhere in the stall, and on the floor. My stall is white, so it labored for me yet i do no longer be responsive to if it may paintings on yet another shade. I left it on there for like quarter-hour and went back. It replaced into super white. I in basic terms grew to become on the bathe and sprayed it down and it replaced into sparkling. desire this helps some.

i would say a solution of bleach, but not if the steps are underwater.

mr clean eraser worked great on mine...