hey guys, I have a 2hp dual speed super II pump. Paired with an older hayward c3000 series quad cartridge filter. I was having issues with it not filtering so the filter elements have been replaced as well as the bottom manifold that was cracked. After doing that whenever I try and vacuum out the dead algae, still I get dead algrea coming back via the returns. I have checked to make sure the filters were seated on the manifold, and the top manifold was pressed firmly into all 4 cartridges. Im lost, any help?