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Old 01/31/2005, 09:31 PM
Anthony Calfo Anthony Calfo is offline
Parapterois heterura
 
Join Date: Nov 2001
Location: Pennsylvania
Posts: 5,141
cheers, Jeff... all clear.

The problems are: 10-20X turnover (or higher) needs to be in the tank, but not necessarily through the overflow. For tanks requiring more flow particularly (as with shallow Acroporid sp, eg) this number is much higher and indeed causes quite a disturbance (even noise) if all run through one overflow box, skimmer box, etc. Hence the popularity of closed loop pumps (tapped into tank walls) and closed loop manifolds (fed by a pump other than the sump return). Thus, a moderate flow can make the display-sump loop (and any inline vessels like the skimmer chamber)... and a separate closed loop pump can handle the bulk of the tank's flow needs.

On your latter question re: the skimmer in a stable open sump... its not bad, but still not as good as a tight skimmer well/box. In a 4' long sump in this example... its even worse for the (large) sump size. Its the same problem as a HOB skimmer that is drawing water from 1, 2 or even 4" below the surface (however stable that might be): proteins get a chance to migrate to the surface and are separated/diluted away from the pump draw.

I think the problem that many folks have in understanding or visualizing this dynamic is the incorrect assumption that all water in the tank and subsequently drawn by the skimmer is "homogeneous" so to speak. When the fact of the matter is that proteins are migrating to the surface... surface of the display... and surface of the sump to your great disadvantage in larger sumps (versus tight little skimmer wells for concentration).

I'm not sure if I've succeeded in explaining that any better. Hmmm...

hoping so
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