Spa Stain

[jwgillis]

I have a spill over fiberglass Spa. It is filled by pool water. A light green stain has developed all around the side of the bottom half of the wall section just above the Spa floor. The rest of the inside of the Spa looks great ... no stains anywhere ... to include the top half of the same stained wall section. My Pool Maintenance Professional states that he uses acid to remove such stains. He is good but I fear the use of acid unless necessary.

How should I attempt to remove the stain?

 

[Bama Rambler]

The first thing to do is to determine what the stain is. Is it metals or organic?
Try a trichlor puck held on a place a little while and see if it lightens it. If it does then it's organic and holding the FC on the high side of normal should lighten it over time. If it doesn't, take some vitamin C tablets and rub them on the stains. If that lightens it then it's metals.

If they're rough feeling then it may be calcium scaling and that's handled differently.

A picture would help too.

 

[jwgillis]

Thanks ... will try and determine per your suggestion. May take a few days ... out of town next 10 days.

 

[jwgillis]

Near as I could determine the stain was neither organic or metals or calcium. I finally found out what 3 of 4 Pool Maintenance professionals in town do if they are hired to get rid of the stain ... they use a mix of muriatic acid and water. They do not want to tell you this as it is not a recommended "fix." I used a mix of 1 cup muriatic acid with 10 cups water ... washed the stain with a cloth ... dried it with a towel immediately ... and got rid of the stain. No harm done to the gel on Spa wall. If it had not worked, or had damaged the Spa Wall, I would have blamed no one ... my decision, my responsibility.