<a href=showthread.php?s=&postid=6875533#post6875533 target=_blank>Originally posted</a> by SDguy
Just keep in mind when people talk about tank turnover, they do not include anything that does not contribute to the flow in the actual tank. For example, don't include your skimmer pump in your calculations, or refugium for that matter, unless either of these items are feeding directly back into the tank. Also, when I say 5X turnover through your sump, I mean 5 times your tank volume, not your sump volume.
You want minimal flow through the actual sump for many reasons. Microbubbles, noise, salt creep, etc. Also, for high flowthrough sumps, they need to be very well designed to not have the problems I just listed. Most are not. As for refugium flow, it again depends on what you want in there...some macroalgae prefer high flow.