Cobalt stains in Fiberglas pool, need help

[Medenjaci]

Hello
I got fiberglass pool and it was resurfaced 5 years ago. 2 years later I started getting Cobalt spots. Local pool cleaning company (Pinch a penny) try getting rid of it and it was unsuccessfull. I found that United Chemicals “Cobalt Cure” worked great but was discontinued and Can’t find it anywhere.
Any suggestions?

PS. I got Salt water pool

 

[Texas Splash]

I would try either some Ascorbic acid (basically Vitamin C tablets) or Oxalic acid. Those have been know to be relatively effective treatments. Once the stains are gone, maintain a good CH level to help prevent recurring. In fact, feel free to post a full set of water results now as well and we can take a look. ABCs of Pool Water Chemistry

Welcome to TFP!

 

[YippeeSkippy]

Do you know how the cobalt got in to the pool? Is someone using odd metal containing algaecides or something?? Is it a plaster pool with fiberglass type finish? It almost looks like rebar coming thru to me.

Welcome to TFP Are you *really* in Sarajevo??

Maddie

 

[JamesW]

Cobalt cure was oxalic acid. Ascorbic acid is what I would suggest.

Cobalt is sometimes used in the fiberglass formula. If it's exposed to oxidation, it can turn black.

 

[Medenjaci]

Thanks for reply all. And I’m from Sarajevo but living in Florida now.
Question:
Is there procedure how to apply Ascorbic Acid and where to get it? Is there certain water chemistry prep I need to do ahead? Etc....
I did try Muriatic Acid applying directly to the spot via PVC pipe and did not notice any deference.

 

[ajw22]

Ascorbic Acid Treatment - Further Reading

www.troublefreepool.com

Where to buy ascorbic acid:

PC NetwoRx Inc.

chemistrystore.com

 

[mknauss]

Thanks for reply all. And I’m from Sarajevo but living in Florida now.

Please change your Location to where the pool is located. That helps us with guidance.
Thank you.

 

[YippeeSkippy]

Medenjaci, have you read this article in our Pool School section yet?

Stains in Your Pool

The stained pool is beyond embarrassing. Our in-depth Guide to remove stains in your pool will help you to remove the stains and prevent them in the future.

www.troublefreepool.com

Maddie