I have a question about some staining issues I am currently having. Here are the most recent test results:
FC 3.5 (bumped it up to 4 last night)
T/A 80 (brought pH down last night and aerated)
CYA 50 (low, I know, added some CYA again. It seems to keep decreasing)
The last OCLT test about two weeks ago was OK.
These two pictures are not great, but has been a little breezy the last several days.
How it started was with one or two spots at the corner of the wall and floor about1" in daimeter, irregular in shape and grey in color. Now there are more appearing as small round dots, dark in color. The chlorine tablet test was inconclusive. However, the increase in number is leading me to believe that this is some kind of black algae. (Of course it is the first week after school ended and the wife doesn't want me to shock the pool just yet, ugh.) My plan is to run the OCLT test tonight and begin shocking after that. Does this sound like an appropriate plan. From reading posts on this I assume I need to rub these spots down with a pumice stone and then shock. Which shock level am I looking for? Pool calc says 16 for normal shock and 29 for mustard algae.