I've been a member here for 3 summer seasons and it's been great. Hoping someone can point me in the right direction on something. First, the details...
-11,000 gallon above ground pool with vinyl liner in CT
- FC hasn't been below 2 ppm all season and is typically between 4-6ppm
- CC has never tested above 0.5 and is usually at or close to 0.
-pH is rock solid at 7.5 all the time
-TA is 80 and has been 80-90 all season
-CYA is 30-35
Recently I noticed what looked like tiny algae blooms on the bottom of the pool. They're barely an inch wide and a very faint green. Seems like they settle into little dips in the pool floor. The water looks crystal clear from a distance, though. You gotta strain to see these little things.
Yesterday I vacuumed, brushed and dumped a little extra liquid chlorine in at night. I run my filter 9 hours each night from 10pm-7am. Tested this morning ( I have a TF 100 test kit) and there wasn't any significant FC loss, yet that tiny algae is there in the same spots (5-6 in total) that were there yesterday.
Do I need to SLAM? Could it possibly be something other than algae? I had algae when I opened the pool in May, but Slammed for 4 days and it was cured (actually turned clear after 1 day but I kept at it to be safe). Would the FC be stable and CC not rise above 0.5 with algae present?
Any advice would be much appreciated!