In-ground fiberglass steps turning yellowish

[Steverino]

We have an in-ground vinyl liner pool with white molded steps that I believe are fiberglass. The pool is now 13 years old and I've been noticing that the steps are yellowish below the waterline. They are still white above the waterline. The pool was regular chlorine for the first two or three years and then I switched to SWG and began using TFP methods to maintain. I do test periodically and keep the chemical parameters within the TFP recommendations.

Any ideas as to why the yellowing is occurring and what one might do about it? I realize it could simply be age and exposure to the combination of water & UV.

Thanks in advance!

 

[mknauss]

Try some vitamin C tablets in a thin sock crushed up a bit. Set it on the steps.

Likely iron.

 

[Steverino]

I'll get some and try that. If the test shows a difference, what's the next step? (pun sorta intended)

 

[mknauss]

You have to decide if you want to just do the steps or the whole pool.

Ascorbic Acid Treatment - Further Reading

www.troublefreepool.com

 

[Steverino]

Thanks - I'll read up!

 

[Steverino]

Just reporting back here... Finally got some vitamin C, crushed it in a fine bag I use for adding stabilizer, and put it on the step. Instant color change - pure white again. What's more, I found all I needed to do was swipe the bag along the steps & risers and it would pretty much immediately turn them white again. As the crushed powder dissipated, of course, the action was more muted. I think for now I'll probably just do that, as staining isn't really noticeable in the rest of the pool (though I'm sure it is there). May try the ascorbic acid at the end of this season or the beginning of next.

Thanks again for the tips, @mknauss !