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View Full Version : Pipe diameter on a Mag 12 return line



SnowHeart
10-23-2008, 11:02 AM
I'm planning out a 90g FOWLR tank with a 29g sump. The return pump is going to be a Mag 12. The pump has a 3/4" outlet but the instructions say the pipes should be double the diameter of the outlet for maximum flow -- so, 1.5". With a 4' head from the sump to the tank, that's a LOT of water that's going to be pushing back on the pump. I sent an e-mail to Danner Mfg to double-check this but haven't heard back. Anyone have experience with this? Is a 1.5" return pipe feasible?

FWIW, I ran this through the head loss calculator on Reef Central at 1.5", and the number it put out was pretty much on target with the Mag 12's specs. When I reduced the pipe diameter to 1", the flow dropped about 40% and was well below spec.

Sploke
10-23-2008, 11:10 AM
I use a 3/4" return line on my 9.5. I probably get some head loss, but I'm not too worried about it. If you rally need to be maxing out the pump's flow for your purposes and have the space to go larger, by all means go 1.5".

SnowHeart
10-23-2008, 2:48 PM
Great. Thanks so much for the input. :)