Boric Acid as stain remover?

[Kelleyaynn]

I just finished the procedure for getting rid of mustard algae. Everything went great, though there were some stains (or something) on the bottom of the pool in spots that would not get clean. They were in the deep end, so I couldn't easily get to them to scrub them by hand, only with the pool brush. Well, I kept the pool at MA shock level for almost 36 hours, and it had a 0 ppm chlorine loss on an OCLT, so I crossed my fingers and decided to go ahead and let the FC level go down and add borates (in the form of boric acid) once the numbers were okay and I balanced the chemistry as needed. Did that this afternoon, and about a half hour after I added the boric acid, the brown stains were gone! :?: :?: :?: Since adding the boric acid was the only change, it must have done something to eradicate the stains. Does anyone know of using boric acid as a stain remover? I'll tell you, it makes me do the happy dance!

Here are pics:

Before:

After:

My sparkly pool: (I just couldn't resist)

 

[chem geek]

Boric acid slightly lowers pH, roughly from 7.5 to 7.2, so maybe that was what had the stains lighten. I don't know of anything specific to boric acid itself that would help with stains.