NJPools.club Community

Hey folks, just got home from my night shift and saw these weird black/green spots all over my pool plaster. Arizona heat's been brutal lately. My Hayward system's running fine, but this looks nasty. Should I shock the pool with chlorine or try something else? Don't want to waste chemicals if it's not algae.

**Hold up!** Before you dump chlorine everywhere—I'm a mom who's dealt with pool stains before. If it's metal staining (common in AZ water), chlorine will make it **worse**. Try the vitamin C test: rub an ascorbic acid tablet on a spot. If it lightens, it's metals. If not, it's algae. Don't panic-treat without testing!

Ugh, I feel you on the budget stress! Ascorbic acid treatments can get pricey... but so can algae blooms if you guess wrong. Maybe try a cheap test first? Like, scrub a spot with a chlorine puck—if it fades quickly, it's organic/algae. If it stays, probably metals. My student wallet says: test small before buying gallons of anything.

Thanks both. @HydroHero29—good call on the vitamin C test. I'll grab some tablets tomorrow after I sleep. @TideTitan39, yeah, the chlorine puck scrub sounds like a quick check. If it's metals, will ascorbic acid hurt my plaster or equipment? Don't want to damage the Hayward setup.

Ascorbic acid is safe for plaster and equipment if used as directed—**but** you must rebalance chemicals after. Metals often come from fill water or corroding parts. Check if your heater or pipes are old. And **please** don't mix treatments! If it's metals, chlorine right after ascorbic acid will just restain it.

Totally agree on no mixing! Also, if it *is* metals, maybe try a sequestrant first? They're cheaper than full ascorbic acid treatments and can hold metals in solution. But if the stains are set, you might need the acid. Update us after testing—my roommate's freaking out about our own pool now 😅