So I have a new pool this year, and it is my second pool to maintain with the TFP method, or BBB (and of course muriatic acid). My previous pool in Texas had a DE filter. It always got the job done. My new pool has a sand filter, and I have sometimes questioned whether or not the thing even came with sand in it. Since we've had it, I've had trouble with clay in it (from our soil during the build from before I got the sod put down) and recently it's gotten green and cloudy though it consistently passes the OCLT. I maintain my pool chemistry and measure the values. Keep my CYA around 35-40 and FC around 5 except when I started having problems I've upped it to 20 sometimes.
Here is the issue--no amount of scrubbing had been clearing my pool of this green stuff. Recently I came to the conclusion that it MUST be pollen. It tends to settle onto the bottom flat surfaces rather than ever being on the sides really. I swept it all into the deep end and vacuumed only to watch it come out of the Jets and cloud the pool again, and subsequently settle to the bottom. So I have been adding DE to my filter, and it seems to be helping some. Add DE, brush, pressure spike, backwash, repeat. I assumed its working because 1) the pressure never goes up with sand alone so the DE must be catching something and 2) I see a bunch of the green stuff in the bubble when I backwash.
But the biggest change was overnight last night. I got free chemicals when I installed the pool and they gave me algaecide. Looks like motor oil kind of. I said screw it and dumped it in the pool. Now I think my pool would've cleared up following my DE method over a few more days, but this morning there was a noticeable difference. I've been wondering if there was a chemical that would cause particles to clump together so they wouldn't sneak past the sand. Maybe that's what the algaecide did? The water wasn't green when I put it in last night, just cloudy, but it was noticeably less cloudy this morning.
Just wondering if anybody has thoughts on this or has experienced anything similar.
P.S. I did at one point take the filter apart and clean it. It had plenty of sand so I guess my suspicions of no sand were wrong...