Not sure how this one works, I got it without a pump with some stuff I got from my aunt a while back. Its just sitting around. If You want it, its yours..... I think its like an overflow type and doesnt use a pump, but not sure.... Looks exactly like this one:

http://images.google.com/imgres?imgu...3Doff%26sa%3DN

Its what they call an Air driven skimmer:





If you want it let me know, Its free for you, but if you have any frags of anything that would be nice too