First, to be honest, those skimmers are the worst. I tried one on my biocube for a while and had to stop because it's almost imposible to dial in. If your cup is filling daily, you have the bubles turned up to high. Use the dial on the hose coming from the pump and cut the air back a bit. You don't want the bubbles overflowing into the cup when you set it up, you want to see them down in the cup chamber. The problem is after you tinker with it for 20 minutes adn get it just right, it will have adjusted itself by the next day and either stopped working or overflowed filling the cup up. After playing with that skimmer for months I got it to produce tea colored water daily but you have to empty the cup every day.
hang that ramora off the side, its 1000x's the skimmer that the biocube one is. Airstone skimmers just don't work properly...
my 2 cents as I've had both the biocube and the ramora...