Originally Posted by Flreefer
Flow in a reef tank usually comes from a combination of the returns and power heads. It doesn't really make any difference where it comes from, just as long as it comes from somewhere. And the information that your returns should be equal to or less than your skimmer output, is ridiculous.
In tank circulation requirements are different depending on what types or corals you have as well. A SPS
dominated tank will require more flow than a LPS
or soft coral dominated tank.
its not "ridiculous" the sump is nothing more than a place for filtration and additional equipment.
lets say you have an ats. that system is very dependent on the correct amount of flow across the screen. more is not more beneficial and less is absolutely detrimental. one way to achieve that flow is having the drain plumbing feed the ats. return pump size has to be matched to that system of filtration.
skimmer or a sump with refugium:
sure if you have a return pump blasting your tank with 1200 gph
or more your skimmer will still work, but if you slow that water flow down to match more of what the skimmers pump is rated for you can obtain a more thoroughly cleaned water amount per pass through the sump. similar to the concept of recirculating skimmers without having to pay the price for one. also if you have a refugium, flow rate through that shouldn't be 1200gph either dependent on what a person uses that for (pod population, isolated dsb
, macro algae) you dont need that kind of flow and again it can be counter productive to some of the benefits.
i am NOT saying that you have not been successful with your tanks using higher flow through you sump. just consider that there are other ways to do things. i dont know if you have had the chance to chat with doug, screen name mr_X, but he ran a beautiful 125g reef with a mag 5 for his return pump. granted, i dont know if i remember the actual specifics properly, and if i dont, i do know im not too far off from them.