If you want to save money, just buy some gfo, a small micron mesh bag and place the bag in an area that gets adequate water flow.

I'm looking at a pic of the skimmer you're talking about. I don't think it would work because it's a passive skimmer that doesn't have a water pump inlet or outlet. I'm lookink at the 14 or 29 biocube model that uses an airstone so let me know if I'm wrong.