For the past few days I've been SLAMming my pool in an effort to get rid of what I *think* is a stubborn case of algae. I don't think it's metal staining, because I rubbed Vitamin C tablets against it and let them sit on top of some of the stain for a few minutes, and I noticed no change.
pH 7.4? (I measured pH at 7.8 before SLAMming, then added muriatic acid followed closely by chlorine without re-testing the pH. I followed the poolcalculator recommendations for the amount of acid to add. Now the pH shows something >8.0, but my understanding is that the pH test is not reliable while SLAMming)
CYA ~45 (This test is highly subjective. I typically just keep going until i can't see the dot at all, no matter how much I shake the tube, or how much light is shining over it. Any tips on making sure I'm checking CYA properly?)
Anyway, I've been at shock level for a few days now. The pool is plaster with Diamond Brite. Twice a day I give it a good hard brushing with a stainless steel brush, and if i really go at it hard with a lot of elbow grease, it seems to make a very slight difference. I see clouds of *something* being kicked up when I brush that I think is algae. Day to day though I feel like I'm not making much progress as the stains aren't changing their look very much.
The "algae" is maybe a greenish-yellowish-tan color. It was recently resurrected from swamp status before I purchased the home, and I'm just trying to get it all the way to clear. Any idea if I might be missing something?