I'm looking at skimmers and I have heard great things about octopus skimmers but they dont have a hang on model. That means I need a sump which i could probably make for a reasonable amount of money. I was also looking at the Coralife super skimmers which do hang on the back. They both run about the same amount of money on ebay (minus the cost of the sump setup). Is the extra cost for the sump the best way to go? Does my tank have to be drilled for a sump or can my lines go over the top in the back? I'm getting my live rock on Tuesday so I kinda need to get this resolved. Thanks!