Based on my past experience with sand filters, if I were you I'd break the filter down and see what the sand looks like. If there's a bunch of green in there, good luck getting it outIf there is, best bet is probably replace the sand again, then forever stay ahead of your pool. Or you could shut off the in and out valves, add more bleach to the standing water and try to kill the crap then backwash it out. Do a search, there are some recent threads about cleaning sand filters that will provide lots of insight.
If you've been staying ahead of your pool and doing regular backwashing and an inspection reveals your sand is in good condition, you may try adding DE to your sand filter, just enough so that the pressure raises 1 psi. Again do a search, lot's of info on this as well, and should help clear the fine particulates that may be getting through your sand assuming it's not an algae issue.

If there is, best bet is probably replace the sand again, then forever stay ahead of your pool. Or you could shut off the in and out valves, add more bleach to the standing water and try to kill the crap then backwash it out. Do a search, there are some recent threads about cleaning sand filters that will provide lots of insight.
Reply With Quote
Thanks fo helping me understand.

Bookmarks