well ideally you should have live rock...thats where they are naturally and live rock will be more than enough filtration for a tank, if you get more than 1 pound per gallon of water that is. And you've got live rock, so honestly, i'd just forget about the hob filter and run it empty. Thats what i do for my 2.5 I got a whisper 20 running empty (well i think i got some rock rubble and a snaill in there lol) and thats all the flow i need. Then i've got 3 pounds about of live rock in the tank. So far my xenia has split like 4 times, my zoas are growing good, and my button polyps are coming back after almost dieing in my other tank. And all the hermits and snails are good too.