Stains on Vinyl

[wollerd]

Hi,
I'm a new home owner that inherited a 33,000 gal inground pool. I took the cover off for the first time in early May and discovered a green mess which I've (with your help) cleaned up nicely. The numbers are great FC=6, CC=0, pH=7.5, TA=110, CH=130, CYA=50 and crystal clear. The pool took a while to clear up and I discovered brown staining on the liner. The stains have straight lines so I don't think it's due to leaves. They run along the bottom as well as up the sides. I had the water tested for metals and it came back negative. There is a heater that's about 10 years old that the previous owner said he only used the first year. I currently have it bypassed. There is also a Nature 2 cartridge installed but hasn't been replaced so it is at least 1 year old. THAT is coming out soon. Does anyone have an idea on how to determine the cause and the best way to remove them? I've attached a photo hoping you can make out the stains. Thanks for any assistance you can provide!

 

[Bama Rambler]

Crush up some vitamin C tablets and put them in a sock or stocking and rub it on the stains. If it lightens them it's metal staining. If it doesn't it's organic and holding the FC at the high normal number will eventually lighten them.

 

[wollerd]

Thank you. I'm shopping for "C" now.

 

[Richard320]

Thank you. I'm shopping for "C" now.

Store brand tablets at the closest CVS, Walgreens, Rite-Aid, whatever you have.

 

[wollerd]

{shrug} It does not appear to be metal staining as it remained the same after a thorough "C" scrubbing.

 

[Vette]

That doesn't brush off with a pool brush, right?

 

[Bama Rambler]

That's not necessarily bad news. At least you won't have to maintain sequestrant.

Raise your FC level to the top of normal level and hold it there. It should lighten the stains over time.

 

[Vette]

If you really want the peace of mind knowing chlorine will take it away, you can rub a trichlor tab on in to see if it lightens.