What is this Stain? How to Remove it?

[osensnolf]

I just took the cover off my hot tub and noticed staining as seen below on one half of my hot tub.

What caused it?

How can I remove it?

I've tried bleach and Mean Green but that did very little.

Thanks!
Steve

 

[Texas Splash]

Looks like some rust stains there. Try some crushed vitamin C tabs. Mush them up really well and hold/rub against those areas to see if that helps.

 

[osensnolf]

Looks like some rust stains there. Try some crushed vitamin C tabs. Mush them up really well and hold/rub against those areas to see if that helps.

I'll get some and give it a try. How soon will I notice a difference? Seconds, minutes, hours, days?

If that doesn't work, do you have another recommendation?

 

[Texas Splash]

You should see a change is just a few minutes or so with the vitamin C. Maybe also try a Magic Eraser gently in a test spot?

 

[osensnolf]

I do not have any vitamin C (without going to buy it). I do have Muriatic acid. Would you recommend me using that? I use it for pH control in the pool which does not have stain issues.

 

[Texas Splash]

Muriatic acid has different properties than vitamin C and Ascorbic acid used to remove iron/rust stains. You can pick-up some vitamin C tabs at your local pharmacy or Wal-Mart pretty cheap. I would try that first though.

 

[osensnolf]

UPDATE: I ended up going with a combination of Vitamin C and Muriatic acid - though not at the same time.