Closed Loop Manifold, Pumps, and Head Loss

[AbraxasFrog]

I am trying to find a pump that can be used with a closed loop manifold. A bulkhead from the display tank will feed pump and the manifold will sit on top of the display.

Manifold will be roughly 48" x 20" with a height of probably 6ft, roughly 5 90 elbows and 4 1/2" nozzles. I am calculating 6ft head plus 1.2 ft head for the horizontal manifold (roughly 1ft of head for every 10ft of horizontal plumb), another 5ft for each elbow and another 1ft for the nozzles. Say, 13-14ft head total.

Does this sound about right?

I need the 4 1/2" nozzles to produce a flow of ~350gph each, for a total flow of ~1400 gph.

So now I need a pump that after 14ft of head loss can produce roughly 1400 gph.

I've used the head loss calculator but the size of the pump (probably something in the 3000gph range) I need cannot be found on the calculator. So I am studying performance curves of various pumps at the head loss I figured on.

Any suggestions as to which pumps I should take a look at, O wise and wonderful reefers?

 

[frank2926]

The only loss to head pressure for height in a close loop is the distance from the intake to the height of the return pipe.

 

[AbraxasFrog]

Thank you for all your help, frank -

Just to clarify, then, if the intake sits 3/4 of the way up my tank (say 5ft) runs down to the ground to the pump which returns that up to the manifold (say 6ft) then the only loss of head pressure is that vertical run of 1ft (between intake and return?)

Do the horizontal runs or elbows account for head loss in a closed loop?

So maybe I am only looking at 9ft of head? This may change matters: I am currently looking at a Dolphin 5600/4700!

 

[frank2926]

All Other head pressure is still in play. But if you use the appropriate size plumbing you can cut it way down. The large external flow pumps account for some head loss already. for example if you use the head loss calculator you will see that A dolphin 2100 gph pump requires 1.5 inch plumbing. If you use it the flow is still about 2100 gph. The way to get around the large sized plumbing required for these pumps is to just run multiple smaller lines. Say 2 1 inch feed lines tied into a 2 inch tee. and on the return run 2 1inch pipes from a 1.5 inch tee up to your manifold