[Delphinus]

He has a lot of caulerpa type algaes growing in that refugium, which is, I suspect, a large part of the reason he's having success, because they're sucking up the nutrients that might otherwise accumulate. Honestly that is a nice tank. I wouldn't say that a skimmer is unnecessary though, but obviously whatever works for someone, works. I like having skimmers, I think they are beneficial, although I agree that as long as nutrient buildup is not a concern then the actual quantification of "necessity" is probably less.

Basically I judge my need for a skimmer by looking at what it pulls out. That brown gunk would be in my tank water if I didn't have a skimmer.. it must be doing SOMEthing good, even if I can't say exactly how much good it's doing.