The type of pump isn't as important as the flow through the skimmer. To be the most effective, it's recommended that you have 1 to 1.5 times the water volume of your system running through the skimmer. What size system are you planning to use it on? Unlike the in sump version of this skimmer, the recirculating skimmers aren't known to overflow as long as they are set up properly so plumbing it outside your sump shouldn't be too big of a worry. If you have room in your sump, though, it won't hurt to set it up there. Whereever you decide to plumb it, just make sure you have the output coming back into your sump above the water level in the sump (do not submerge the skimmer's output as this will cause back pressure).