Herbie overflows and gravity fed skimmer?

[Delphinus]

Thanks!

What's the consensus regarding recirculation style skimmers anyhow? The one thing that strikes me as maybe a question mark ... if the skimmer was fed ONLY via the overflow of the main display, then any residual DOC in the water column can only "exit" via the main display overflow. Ie., if the skimmer doesn't fully extract all the "nasties" - the nasties then have to go through the sump, and then randomly through any frag tank and/or refugium back into the main display and back over the overflow for the skimmer to have any "second chances" to extract them. Maybe this is a gross oversimplication of skimmer theory and I'm wrong, but I wonder if this could be construed as a weakness in this idea... over just having the skimmer draw from the sump and return to the sump and recirculate that way.