Dumb CL pump question: 0' head loss on closed loop, right?

eameres · 09/19/2006, 06:34 AM

just want to be certain I have this right. On a closed loop there is 0% loss due to head pressure since the water goes down to the pump with the same pressure that it comes back up with. There is loss due to elbows, valves, etc, though.

Put a simpler way, since water stays in the pipes going to and from the pump without the pump being turned on, head pressure has no impact on the pump. Right?

So in a closed loop is it best to go for a pump that has more flow and less pressure, or vice versa?

Aquaduck · 09/19/2006, 07:46 AM

Yep. That's correct.

SDguy · 09/19/2006, 08:54 AM

Yes, you are correct about the head loss.

No, closed loops do not require pressure rated pumps. Waste of electricity IMO.

eameres · 09/19/2006, 08:56 AM

so an oceanrunner 6500 which does 1700gph at lower pressure with under 120 watts might be an ideal choice for a closed loop pump?

RichConley · 09/19/2006, 09:52 AM

Quote:

Originally posted by eameres
so an oceanrunner 6500 which does 1700gph at lower pressure with under 120 watts might be an ideal choice for a closed loop pump?

Or you could look at a sequence snapper that does 2400 gph at 90w.

Or a tinymight that does 1900 at about 90w.

eameres · 09/19/2006, 09:56 AM

ooooh, ahhhhhhh, sounds nice!

eameres · 09/19/2006, 10:13 AM

I wonder how a SCWD or two would impact a sequence snapper on a closed loop.

RichConley · 09/19/2006, 10:16 AM

Quote:

Originally posted by eameres
I wonder how a SCWD or two would impact a sequence snapper on a closed loop.

It would cause lots of problems.

With any pump over 1500gph, you should be looking at 1.5" plumbing, minimum.

The scwd is 3/8". Thats a serious restriction, and none of these pumps are made to handle that sort of backpressure. They'd still work fine, but you lose a ton of flow.

Either go with a supersquirt, or look into heavily modifying a sqwd. Theres some good comments in this thread:
http://reefcentral.com/forums/showth...9&goto=newpost

eameres · 09/19/2006, 12:12 PM

how about a scwd off a manifold with other paths for the flow to take as well? could flow be balanced with valves?

mg426 · 09/19/2006, 12:43 PM

I use the SCWDs, they are pretty cheap and mine have worked great. You do however lose a good bit of flow.

eameres · 09/19/2006, 12:53 PM

what pump are you running them with and in what configuration?

Thanks!

RichConley · 09/19/2006, 12:58 PM

Quote:

Originally posted by eameres
how about a scwd off a manifold with other paths for the flow to take as well? could flow be balanced with valves?

That would most likely work just fine.

09/19/2006, 06:34 AM	#1
eameres Registered Member Join Date: Apr 2004 Location: Albany, NY Posts: 406	Dumb CL pump question: 0' head loss on closed loop, right? just want to be certain I have this right. On a closed loop there is 0% loss due to head pressure since the water goes down to the pump with the same pressure that it comes back up with. There is loss due to elbows, valves, etc, though. Put a simpler way, since water stays in the pipes going to and from the pump without the pump being turned on, head pressure has no impact on the pump. Right? So in a closed loop is it best to go for a pump that has more flow and less pressure, or vice versa?

09/19/2006, 08:54 AM	#3
SDguy Fish heads unite! Join Date: Mar 2003 Location: San Diego Posts: 23,384	Yes, you are correct about the head loss. No, closed loops do not require pressure rated pumps. Waste of electricity IMO. __________________ Peter SDMAS member Marine tanks since 1989. ><((((º>`·.¸¸.·´¯`·.¸.·´¯`·...¸><((((º> ·´¯`·.¸. , . .·´¯`·.. ><((((º> Current Tank Info: 240g butterfly and angel FOWLR. 15g QT.

09/19/2006, 12:43 PM	#10
mg426 Registered Member Join Date: Jan 2006 Location: maryland Posts: 6,923	I use the SCWDs, they are pretty cheap and mine have worked great. You do however lose a good bit of flow. __________________ I found a way to make a small fortune running a reef tank. Start with a large fortune. Unofficial President of the SEACLONE haters club Current Tank Info: 125 mixed reef 110 lbs LR, 1x250watt XM 20K MH 2x175watt XM 20K MH on Magetics 2X96 watt actinic PC, 220 watt VHO actinic, 30 gallon refugium, closed loop system powered by Sequence Dart MSX 200 skimmer 38 gallon sump, Oceansmotions squirt

09/19/2006, 07:46 AM	#2
Aquaduck Registered Member Join Date: Mar 2004 Location: Waterloo, Ont. Canada Posts: 1,076	Yep. That's correct.

09/19/2006, 08:56 AM	#4
eameres Registered Member Join Date: Apr 2004 Location: Albany, NY Posts: 406	so an oceanrunner 6500 which does 1700gph at lower pressure with under 120 watts might be an ideal choice for a closed loop pump?

09/19/2006, 09:56 AM	#6
eameres Registered Member Join Date: Apr 2004 Location: Albany, NY Posts: 406	ooooh, ahhhhhhh, sounds nice!

09/19/2006, 10:13 AM	#7
eameres Registered Member Join Date: Apr 2004 Location: Albany, NY Posts: 406	I wonder how a SCWD or two would impact a sequence snapper on a closed loop.

09/19/2006, 12:12 PM	#9
eameres Registered Member Join Date: Apr 2004 Location: Albany, NY Posts: 406	how about a scwd off a manifold with other paths for the flow to take as well? could flow be balanced with valves?

09/19/2006, 12:53 PM	#11
eameres Registered Member Join Date: Apr 2004 Location: Albany, NY Posts: 406	what pump are you running them with and in what configuration? Thanks!