Pool Stain

[Nick's Pool]

Good afternoon,

I am trying to identify what type of stains these are on my plaster pool. I live in Florida and sure, do leaves sometimes touch the bottom, yes! But I have never seen these until this year. I keep my water balanced using the SWG suggested Salt Water Chemicals Chart. Recent Test:
FC - 4.5
PH - 7.5
ALK - 70
CH - 350
CYA - 80
Salt - 3400
Borates - 30

I tried using a sock full of vitamin C tablets and placing directly on the stain but nothing happened. Does anyone know the easiest way to remove these reddish/brown spots? Thanks so much.

Nick

 

[mknauss]

Any seed pods or other items from the trees?

If not iron, I would think it is organic. A tannin or something similar.

 

[Nick's Pool]

Thanks so much. Any recommendations on how to get those out without draining the pool. Thanks