Pump Output vs. Filter Circulation

[chkthisoutt]

For a canister filter, whats the difference between Pump Output and Filter Circulaton?

For example, for a Fluval 205, the Pump Output is stated to be 180 gph but the Filter Circulaton is only 110 gph.

Am I right in assuming the filter circulation is lower due to media resistance and height to be pumped?

 

[Hound]

Pump output is what the pump can do when sitting in a bucket of water without anything actually hooked up to it. Circulation rate is the output after pulling water thru filter media and then up and out an output hose. Now since manufacturers can't know how long your hoses are or how far below the tank the filter sits most won't hazard a guess at circulation rates. I'm not sure what testing criteria Hagen uses on their fluval filters, but they are about the only manufacturer that I am aware of that lists any circulation numbers. Most filters state a maximum flow rate which is probably equivalent to auto manufacturers saying the an engine has 150 horsepower without anything connected to it.

 

[chkthisoutt]

Yup, that kind of explains it. Thanks.