Question on Closed Loop Pressure

[oceancritters]

Hi all,

Few months reader and first time poster.

Just a question on closed loop... I was told that the pump's GPH is unaffected regardless of how many elbows and vertical lift you have as long as it is in a closed loop system. Is this true?

Thanks.

Drew

 

[sharkdude]

yes and no. there is some loss due to friction, but theoretically, if input path and height is same as output, it balances for a net of zero.

now if you draw from a hole mid tank and then return to top of tank, head pressure would be difference in height of input hole and output return.

think about how cannister filters work. crappy little pumps, but because input siphon and weight of water balances against output, you can still get 200-600gph on outflow depending on cannister model, etc

if its a true closed loop system, a 1000 gph pump will achive nearly 1000 gph on the output nozzle.