How to clean white mineral deposits at waterline in fiberglass pool?

[otherchuck]

Greetings all!

We have a sand-colored fiberglass pool, and ridiculously hard water. There is, of course, a hazy white section around the waterline that drives my wife absolutely nuts. We have currently drained the pool a little (beneath skimmer) for now to fix a leak around the skimmer, so now would be the perfect time to try to 'dissolve' or otherwise eradicate that deposit zone. Are there any chemicals or strategies we should try? I know people have suggested I use vinegar to clean the hard water deposits off my aquarium...and sadly that doesn't work miracles. In any case, I am wide open to suggestions! Thanx!

Otherchuck

 

[csconner]

hello otherchuck,

Are you positive it’s hard water scale?

I have a FG pool (blue) and the first year (before TFP) I first noticed some white scale in multiple locations at last years open. Interesting part is its not on the FG surface it’s deeper. I tried magic eraser and light sanding (800 grit) no difference. When I get close it’s clear it’s under the surface as FG surface remains smooth.

this year at opening no change in the scale.

I attribte it to using “pool store chemicals” year one.
I also believe maintaining CH about 550 helped the issue.

Do you have any picture?
I’d be interested in comparing..
I’ve attached a picture from todays opening you can clearly see the “scaling”

one more item, see this for a much deeper examination of the issue by @TexasSplash

Fiberglass Discoloration (Faded & Chalky) - My Story

DISCLAIMER The following is a dialog of my own personal experience. Any processes used, chemically or otherwise, were performed strictly on my own without any recommendations from Trouble Free Pools. FUTURE POSTING I am trying to keep this thread streamlined with just my own progress for all...

www.troublefreepool.com

 

[Texas Splash]

I tend to agree with csconner above. As a test, you could try applying some muriatic acid to the exposed area. If it reacts with a fizzle you might be lucky with scale, but don't be surprised if you get no reaction. That's what happened to me as well.

 

[otherchuck]

Thanks! Wow, Texas Splash's "Fiberglass Discoloration (Faded and Chalky)" post is epic and very helpful! I only suggested "hard water deposits" in my original post because...well, because I thought with our ridiculously hard water (we are on a well system) we tend to get hard water deposits on sinks, faucets etc., so that seemed like the likliest culprit As it turns out, the haze is most definitely not just "at the water line;" we have lowered the water level currently by about 8 inches because we have to seal a leak at the skimmer (waiting for sealant to arrive), and the hazy bit is from the regular water line, to the current waterline. In other words, it is an "underwater" thing you don't see when the water level is high enough to cover it. I am now going to take the coward's way out, and refer my wife (our designated aqua-chemist, and the one who is is more bothered by this than I am), to this thread. Thanx again!

Otherchuck