Well, I've been a member for awhile here now and feel that I have a full grasp of everything. In fact, I often help newbies with their problems because I've learned so much on this site.
My CYA is 50 and I maintain my FC religiously between 4-6 ppm with manual dosing. I am OCD about testing my FC, I often do it every day and for sure no less than every other day. My pool is the sparkliest pool on the block and I take great pride in it. Everyone who sees it comments how pretty and clean it is. Well they do say that Pride comes before a fall, right?
Well I think my mistake was letting my FC drift too close to the 4 number. We've had a ton of rain here in the last week and I've had to do several partial drains and still even overflowed a bit. ONE time I checked my FC and it was at 3. It has been right at 4 a couple of times too, though.
Bottom line is that I think I have algae. I was hoping it was just dirt with the extra rain we've had but it sure looks fuzzy and it's clinging to the walls which dirt never does. I will do an OCLT tonight to confirm.
I think the lesson is maybe not to push it too close to the minimum FC level, even if you test almost every day like I do. From now on I think I will keep it between 6-8 to be safe.
I'm also hoping this will be a short SLAM, if necessary.
Anybody else had this happen while just going under for a brief time?