My pool is clear but I see what seems like black algae on the steps of my pebble tec pool and it's getting worse. My FC won't maintain and keep dropping down to zero after I add bleach or super chlorinate. My CYA is somewhere 70-80 and PH is within range. I had this problem about a month ago. I slammed the pool and got rid of the black algae and FC maintained for couple of weeks but now the problem is back.
I understand that it might be the algae that consumed the FC and last time when I slammed the pool, may be I didn't slam enough to kill all the black algae and it's back and killing the FC. Does it sound like a good assumption?
Also, I use Pool Solutions CYA because I found a good deal on the 25 lbs container, and the dot test shows a good number. My question is, if the dot test shows good number, does it absolutely mean that my CYA is good? I don't know how the test works but just worry that may be the test can be fooled by whatever chemical they have in there.