How long has the skimmer been running? Might take a while to break it in... It did take a few days for my remora pro to stop spitting bubbles back into the tank.
Maybe you could try adding a sponge on the outlet... and adjusting it a bit. I've never had a coralife but I have heard some good stuff on them. Maybe some others on the forums can help.
For What Its Worth.. I found this from google.
Posted by dirtyreefer on 07/07/2005 07:12 PM:
For all you people with extra microbubbles or collection cup overflows, a fellow Canadian reefer emailed Coralife about their problem. Here is their response, which might be helpful. I found that this was my problem when I setup my 220.
Thank you, for your most recent purchase of our Coralife Super Skimmer. We are sorry to hear about your experience with our product. It does sound like the skimmer is not set up properly though. The way you wrote your email I understand that you are probably having water come out the air vent on top of the output tubing. If this is the case it sounds as if the bubble trap is not set up properly. You will want to make sure that the top of the bubble trap is at the same level as your water line of the aquarium or 1/16" above. Make sure your black sponge is on top and the white sponge is on the bottom. Then make sure the end of your outlet tubing is no more than 1/2" to 1" in the black sponge (you may have to cut the tubing). What was happening is the skimmer had back pressure on the outlet hose. Since protein skimmers are not pressurized system the only way for water to get out is through the collection cup. That is probably why you where having problems. The other item we include with the model 65 Super Skimmer is a flow control valve. If the outlet is set up properly and you are still having problems attach the flow valve to the outlet of the water pump and valve it back a little.
Is your output tubing under water? If so that could be some of the problem. The only way for water to go into the collection cup is because the output has back pressure on it and its not able to get rid of the water going in the unit. The only other problem I can think of is if you do not have the tubing going out and down right away this will also cause back pressure. The output tubing can not run horizontally. Otherwise if none of this is the problem then you can either return it to the company you bought it from or return it to us for a replacement.