It sounds like ur using it as a hang-on.....correct?? (not in sump)
I have the same skimmer and found that i have to turn it off during feedings and not turn it back on for about an hour or 2 (min). I think this is benificial to do anyway because the skimmer tend to pull out alot of the micro food that u just added. I feed my tank at around 8pm, so the skimmer goes off at around 7:30 via a timer (home depot or lowes - $15-18) and then the skimmer doesnt turn back on till about 4am... I only run it about 15 hours a day. This seems to work well for me.
As far as the micro bubbles go, make sure the power on the pump is turned all the way up. You can check this by turning the whole intake section so that the bottom of the unit is facing out. The power cord will be coming from the top/front part of the pump.......hopefully thats makes sense to u.....if it doesnt, i can shoot u a few pics of mine.
This helped on mine. I accidentally turned mine down while cleaning it one day and didnt realize for at least a month.
If that doesnt work, try adjusting the height of your overflow cup (the one in the tank) and the lenghth of the hose feeding into it
good luck , let me know how u make out.
Very temperamental skimmer but works well when its working right
