Cone is simply a shape, now how much effective is it I can not say one way or another, there has to be a reason people are willing to pay the big bucks that they command though. (More than just hype too

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Recirculating simply has at least one pump hooked to the skimmer that sucks water directly from it, and reinjects it, the idea being that you can more slowly put water into the skimmer while continually moving it around, of course that means you need at least one more pump or to plumb your overflow directly into your skimmer. It is interesting to note however that of the really efficient high end skimmers, not many are recirculating, but rather employ a rather good pump instead.
I personally think recirculating skimmers can be overrated, since bubble diffuser plates have come into the mix you can toss a more powerful pump on any particular skimmer body without too much in the way of issues. However this is just my opinion, not necessarily a statement of fact
