Pool Stain Help - Ascorbic vs Muratic? What am I looking at?

38372

New member
Apr 21, 2025
2
Michigan
Hey Everyone,

Im looking for some help on how to remove some staining around the entire pool on the first 8-10" below the tile line. I am semi new to pool ownership here as this will be our second season but I have done everything myself from the beginning. I recently reached out to the previous owner who told me the stain below the tile line appeared after the first winter. The pool is 14 years old and has never been refinished. The marcite is certainly starting to show some wear. A friend has mentioned doing an ascorbic acid treatment on it as he was thinking the stains were metal. Im starting to think the stains are organic so I wanted to get some opinions on what im looking at and how to tackle this and or if its even worth doing as acid bath treatment with such an old finish. I have attached two picture below. One you can see the stain line below the tile. The second you can see where it almost looks like a heavy cleaner of sort had dripped into the pool over winter and removed some of the finish. Both are discolored obviously. Perhaps its best to try a small portion somehow and see how it responds before moving onto the entire pool? Any suggestions for that? Thanks
 
Welcome to TFP!

Your pictures didn’t make it.

Organic stains will be cleared by chlorine. Ascorbic acid is most beneficial in the case of iron staining. For stain removal, muriatic acid is primarily used to etch away a surface layer to expose new material underneath. Check out Stains in Your Pool for more info.