When we first got our pool 20 some years ago it came with a Sta-Rite PLD-50, which worked fairly well until we had to replace it recently. The PLD-50 is a unique cartridge/DE hybrid filter. Our only complaint was that we had to disassemble it to clean it every couple weeks. It has nothing like a backwash. When it came time to replace I thought going with a larger filter might mean less frequent cleaning. Makes sense? So I went with what I thought was the next size up, the Sta-Rite PLM-100. The problem was the PLM-100 manual gave no guidance on how much DE to add. The PLD-50 uses 6 lbs, so it might make sense that the PLM-100 uses twice that? But we ended up cleaning it every other day. Yes, we have algae problems. Common wisdom says algae clogs filters. But every other day made no sense. Long story shorter, the PLM-100 is apparently not a cartridge/DE hybrid? It uses no DE? It doesn't say that in the manual. So hopefully we haven't ruined the filter. BTW, the outside housing mentions to add a DE slurry at startup, but doesn't give an amount. Very confused.
