We just opened the pool 12 days ago and the pool has been in swimming condition for the past few days. I've been keeping the pool at shock levels on a daily basis and find what I believe is dead algae at the bottom each day, but less and less. An overnight FC loss test will happen soon but I'm keeping FC levels up for now.
I'm running the pool 24x7 for now and have been cleaning and backwashing on about a daily basis. I'm noticing that the dead algae may be accompanied by sand or some other gritty material. This seems to be mainly around the water returns which made me wonder if it's sand from the filter, and may be indicative of a problem. The pool pro who opened the pool for us was here a couple days ago doing some other work, and he suggested that frequent backwashing can make the filter less efficient at filtering out smaller particulate matter, and we'll probably see less of this grit after a few days without backwashing.
Does that make sense? Can you really backwash too much? Unfortunately the pressure gauge on the filter is shot, but we're replacing that tomorrow or Tuesday. Hopefully once the gauge works I'll have a better sense of when I need to backwash, and when to resist the urge. Our waste water goes out into the street, and I think I just enjoy seeing all that murky water wash away.
Swimming today I tried to feel some of the sediment to see just what it was or at least what it felt like. Some of it goes into solution pretty much on contact and I can't say I felt anything that I could describe. I'm guessing that's the dead algae. The other stuff is gritty and felt like fine and fairly regular sand. I suppose I could take a sample and dry it out if that helps establish what it is, but if the filter can start trapping it, I guess it may not matter.