Hi all, I could use some guidance on an issue I'm having in my spa. It's a raised spa with spillover into the pool and the returns are at varying heights in the spa. This pool is a new build and all has been well since December's startup. That is, until today. The lowest of the returns in the spa has developed a rust looking mark on the plaster, and the actual plastic ring and jet have this same color as well. It doesn't wipe off the plastic, it's seemingly stained. Anyone see this before? I'm doing the water maintenance so far which has mainly been adding about 1/4 gallon of chlorine every 3 days or so as needed to keep it in range and acid of no more that 1/8 gallon per dose to keep the PH in check which seems to be happiest at 7.6. I don't put acid in but once about every 4-5 days. Any ideas are appreciated!
Here is an idea: Try rubbing it with a puck... if it goes away, it is organic and will clear with bleach.