Flow rate of air pumps

[wickette]

Seems like a basic question but I can't find an answer to it. Im purposing some spare equipment, trying to get a rough idea of what my air pumps are capable of...

If an air pump pumps 25 gph air and all conditions are optimal (uplift height, filter depth, tube diameter, bubble size, media, etc) is the water flow going to be more or less than the 25gph air flow.

I ASSUME a a bubble of air would at most lift the same size bubble of water and wont ever be 100% efficient so water flow is always less than air flow.

If thats true an air pumps for "upto 40gallons" has 1/7 the flow at most vs a power head of the same brand rated "upto 40 gallons" (25gph vs 180gph) does that sound right or am I missing something?

 

[Big G]

Bump

 

[wickette]

answer my own question, read on other forums water flow is a fraction of air flow,

Confusingly I set up a 15gph air pump powered HOB, timed how long it took to fill the 0.4g capacity, I got 13gph which holds true to the belief but keep in mind uplift water above water level createsa lot morep ressure redung flow, and air hobs dont use bubbler lose a big fraction of potential water flow. And chaces arethe 15gph air claim is if youre using a short air tube, not 3-4'.

I now think air pumps move more or less the same amout of water as air. But theoretically might atleast be able to move double but thats a guess