After endless study I'm back to square one regarding filtration. The plan is to have a 40 gallon display tank, 20 gallon sump (as yet the sump is blank untill I decide what it would be best fitted for). Livestock will be: pair of clown fish with anemone, one yellow tang, some hermit crabs and shrimps. I plan to have about 15 kg of live rock. No plans for coral. Any suggestions please regarding type of filtration I should use for this setup.