i have an rs80 and i have it submerged about 8in like recommended and it works wonderfully. i've never been happier with a skimmer, pristine water and no more algae on the sand! how long have you had it? they take some time break in and you have to play around with it like other have stated. i just turned mine on after being off a couple days and it's going crazy with bubbles too, but it should calm down soon.