I finished my SLAM (in another thread) just over a month ago. Since then I have been carefully maintaining proper levels of FC based on my CYA.
I noticed a week ago what looked like a "clump" of algae on the threads of one of the returns. Thought maybe I had missed brushing it from before (although I didn't think so). I brushed it off and went on my merry way.
I was just commenting to a friend this past week (jinx!!) that for several years I saw algae on the grout of my tiles all the time and didn't see that anymore. Well, today, I noticed it was starting again. It doesn't form on the fiberglass, just on the tile grout (or areas where the grout has broken off). When I scratched at the little black mound with my fingernail, it was obviously green underneath and I know that it wasn't there earlier this week.
I have been testing chlorine daily. PH every two or 3 days and everything else other than CYA and CH once a week. CH and CYI I only test when something happened that could change them.
Test results just now :
FC 7.5 (I usually test in the evening and add what is needed to bring it back up to 9)
So, everything still seems correct. Assuming it's black algae, I found the pool school article and I will bump my FC up to between high normal and SLAM level. And, brush daily.
Before I found TFP, I had purchased "PhosFree" from Leslie's. But, I haven't used it... it's just sitting in the garage. Is it worth adding?
I'm surprised that this has occurred after several weeks of faithfully following the protocol so, I'm looking to figure out what else I need to be doing to prevent it from occurring again. Or, is black algae just that much of a pain that I will just have to always watch for it?