The Remora is an injection skimmer, no venturi or valves to adjust. Micro bubbles will occure until the skimmer breaks in, it took mine a couple of weeks (though it started to skim on day one.) AquaC also makes an overflow box designed to eliminate microbubbles on the remora and remora pro, I believe marine depot sells them. If your tank is big enough (mine is a hex and it won't fit.) I however, have a buddy that has one, and it appers to work, I have never hard him complain of micro bubbles. You might also try putting a sponge in the spillway.. .haven't tried that, so not sure if the sponge would effect the skimmers workings or not.