Removing scale from fiberglass spa

[Kcherrix123]

I’m sorry if this has been answered already. I searched the forums and saw blasting and remove scale from tile and hard surfaces, but not fiberglass spas. We bought our spa 7 years ago and this year, for the first time, after I drained it and wiped it down for the summer, I noticed a boy 45% of the surface

 

[Richard320]

Search "no drain acid wash" up above. That's what I'd try.

You can't get in and grind on it and spritzing the empty spa with acid pretty much guarantees destroyed clothes, dry skin, and lung problems.

 

[Kcherrix123]

Search "no drain acid wash" up above. That's what I'd try.

You can't get in and grind on it and spritzing the empty spa with acid pretty much guarantees destroyed clothes, dry skin, and lung problems.

So to use something like this, I’d have to refill it? I worry about acid on the fiberglass surface.

 

[Richard320]

So to use something like this, I’d have to refill it? I worry about acid on the fiberglass surface.

One way or another, the solution is going to be acid. You can't scrape or sand it off.

Maybe try a weaker acid like vinegar while it's empty? If it foams and lifts off you're good.

 

[duraleigh]

Search "no drain acid wash" up above. That's what I'd try.

I absolutely agree. I can't think of anything else that would give you good results.