swc skimmer

Please help anyone. When I first putting swc 120 skimmer into the sump it work fine, I see a lot skim and foam. After a week I do WC, I don't see the skimming and foam anymore, all I see is bubble at the bottom of the cup, I try to turn water level up but that maximum they can go, they can not...

Hi all Finally got the tank broken down and wanted to repost what I have for sale. 125 G RR marineland tank with original stand and DIY canopy. Has all the plumbing and a DIY acrylic sump that maximizes the space in the stand with out modifiing it. 300.00 pics...