Looking for an in sump or HOB? I didn't have enough space on my sump for an in sump model but I bought a BH-1000 Octopus skimmer (its the one with needle wheel pump, the bh-100-300 are pumps) to hang on my sump and love it. If you have room in your sump the 4" model would be enough. Aqua Cave has great prices on them and free shipping on 175.00 orders.