want help, Mag-drive 7 flow seems low

[Paradoxed]

I am making a 20 gal sump for my 30 gal reef, and using an overflow to the sump with the following for the return

getting 225GPH with this configuration,
all 3/4 PVC, Mag-drive 7 going into a 45, union, ball valve, another 45, into the scwd, then out thru 3 90's on each side.

I realize the scwd can slow flow, but this seems a bit much, testing flow at the union, I get 450GPH.
I am posting this here because Marine depot tells me this is pretty normal and the pump mfg'r (dannermfg.com) won't answer my emails.

flow at the union of 450gph seems low, is this normal?


Thanks

 

[Anonymous]

I realize the scwd can slow flow

Have you tested flow rate with the SCWD out of the equation?

I've heard people reporting that it can cut flow by more than 50% in some cases so I'd check it if it were me...

 

[Anonymous]

Mag pumps flow rates drop WAY off the more head pressure. Somewhere I saw a chart. that listed flow for each pump at differnt pressures.

I'm setting up the exact setup you have there, so I'm gonna watch this thread closely.

B

 

[liquid]

Try using this to solve your flow question:

http://reefs.org/pumps/

If it is the case that a SCWD will cut flow by 50% then it doesn't suprise me in the least that your flow dropped to ~200 gph.

Shane

 

[Paradoxed]

cool, did the chart

First time was the following config:

tested: 225gph (full run)

calculator shows: Total losses are 4.87 feet of head pressure, or 2.1 PSI. with a flow rate of 434 GPH (calculated without scwd in equation)
Seems ok


Second test was almost completely diassembled:

tested: 450gph (disconnected at union, so it's mag7-->3/4 SXF coupling-->6" run of 3/4-->45-->1/2 the union, because it's disconnect point)

Calculator shows: Total losses are 1.66 feet of head pressure, or 0.72 PSI. with a flow rate of 599 GPH

second test is calculator at 599 compared to actual of 450

so, I guess my question is: is this enough to worry about? and is this pretty normal to see these types of differences in second test between "advertised" flow and real world?

Marine depot says it's normal, mfgr won't respond to emails.

thanks

 

[Anonymous]

if you can get them to ever respond let me know i have a few questions for them as well

 

[Johnsteph10]

good luck getting dannermfg to respond. never heard of them replying back to anyone.

too bad their pumps are good for the money or i'd have to rant against them.

John

 

[Anonymous]

tested: 225gph (full run)

calculator shows: Total losses are 4.87 feet of head pressure, or 2.1 PSI. with a flow rate of 434 GPH (calculated without scwd in equation)
Seems ok

So you're getting ~434 GPH @ ~5ft head w/o SCWD & ~225 GPH @ ~5ft head w/ SCWD?

Sounds about par for course from everything I've read..

But you said "calculated" .... - that mean no actual test w/o SCWD?

Norm