And actually the only real difference between the two designs is the height of "F".

Interesting using the check valve.

And I so use a venturi on a powerhead also. Without a check valve. With water a small amount of water is just recirculated back to the tank is all.


But then I guess pwerheads, aqualifters, check valves can all fail at some point.

__________________
fw leiden since 1979, fo salt since 1979, mixed reef 55g 2002-2009. Strong emphasis on the tank taking care of itself. Balanced with plant life, no water changes, tap water, no filters in FW. Only dosing calcium, alk, mag in marine reef tanks. http://www.aquariumforum.com/f15/my-...ods-26410.html
recent tanks (till 2009) 7 years- 10g FW leiden 7 yrs, 55g mixed reef 7, 2 yrs, 20g FW leiden, 10 g fw leiden , 29g mixed reef, current tank 55g leiden