Removing stains and rust from metal stairs/screw and plastic.

[JoeyV]

I have some rusting stains on screws holding skimmer plate and stairs. Also some staining on the plastic skimmer plate as well. I used ascorbic acid and also tried muriatic acid. I got the stains off of the plastic under the water but the portion above the water is still discolored. See pics below. What can I use to get rid of the rust stains and discolored plastic above the water? Also please take a look at the pic of the one leg of my stairs. What is that? Is it removable?

 

[JoyfulNoise]

The plastic face of the skimmer can usually be cleaned using a Mr. Clean Magic Eraser sponge. As for the metal, it's stainless steel so I'm not sure what the deposits are but if it's rusting, then it's likely not marine grade (316/316L) SS. You can lower the water level (or remove the ladder) and scrub those areas with Bar Keeper's Friend liquid cleaner. It's oxalic acid and very fine polishing paste that will remove oxidized iron. However, if the stainless steel is compromised, it's only a matter of time before the corrosion starts to happen more quickly. In the future, you might consider replacing the metal ladder with a high quality fiberglass/composite ladder.