Who rates skimmers

[sphelps]

Originally Posted by Canadian

This is somewhat dependent on your sump layout but think of this analogy:

If I drop a small piece of sinking pellet food down my overflow and I have one of two options:

a) High flow rate through my sump
b) Low flow rate through my sump

Which one do you think is most likely to allow the intake/suction of the skimmer intake to pull in the piece of food? The one ripping the current past the skimmer or the one slowly plodding along?

I'd certainly rather pull mechanical chunks of organic waste out of my tank before they have a chance to break down and then become part of the chemical soup in the water.

While I see your view and get what you're trying to say two problems exist with your example. First a skimmer removes dissolved organics which I guess can be compared with food but we don't place organics/food in our overflow but rather rely on flow to get them there. So in real life that piece of food will get to the overflow faster if flow is higher, resulting in going to the sump sooner. Dissolved organics should be looked at differently than a food pellet, its concentration is distributed throughout the tank not in one particular location.

The second problem is the assumption less flow through the sump results in more water being filtered though the skimmer before going back to the display. First these are independent, the skimmer outputs the same as it takes in. So exactly how could one possibly determine how much overflow water is actually going in the skimmer and not simply bypassing it completely? With a lower turnover the amount of water being constantly recycled through the skimmer could actually be higher meaning less overflow water is going in compared to high turnover.

Regardless the point I'm making is that the two are completely independent. Dissolved organics are dissolved meaning the concentration throughout the tank will be virtually constant. The amount of organics taken in by a skimmer is essentially constant and independent from the water flow moving past it. High or low turnover (in limits), a standard in sump skimmer will work the same.

Lower sump flow rates are related to lower noise and less air bubbles but not skimmer performance. The only reading I've seen relating these two suggest higher flow rates as it will "keep solids in suspension, which increases feeding opportunities by fishes and invertebrates, and improves filter/skimmer opportunities to export such matter in a well-designed system"