I would have to say the most important items with filtration are that it will filter a recommended volume of water per hour AND that it matches the type of fish you have or plan to have. That goes for SW and FW. You shouldn't have a raging river filter for a stagnant water fish, nor should you have an algae pond set up for a shark. Hope that helps. Btw, I'm a Fluval guy all the way. Both canister and HOB and I can hear my air pumps over my filters.