I have a fission nano in our 29g and if it gets cleaned every week it skims "fairly" dark, but still wet. The real problem is wet skimming wastes more water and the fission's performance is seriously impacted if the water level changes.
Clean filter pads ("pristine", actually) are the key to stopping microbubbles with the fission. You can soak the old filter pads in bleach to make them last a little longer, just make sure you rinse them really well with a dechlorinator. Don't rub or squeeze them when you clean them, though, because if they tear or pull apart they'll be useless and you'll see microbubbles again.
I keep a clothes pin clamped onto the airline tube we've got attached to the drain and unclip it once or twice a day to drain the cup. I've got the other end running into an old 2 liter soda bottle which will almost fill itself once a week -- for the amount of stuff this
skimmer pulls out with 2 liters of water a more efficient
skimmer would probably only pull a cup or so of water -- it does pull it out, just not as efficiently.
