Why do people use 1" pipe on there return pumps?

[Dan F]

This is for a gravity fed flow (i.e. overflow to sump). On the return lines you have a pressurized flow, which can push a much higher flow rate through the pipe. The same volume flowing through a smaller pipe will have a greater flow velocity than in a larger pipe.

Check out this chart for more info on pressurized flow rates.

Great link!

I do have to point out that the figures for pressurized flow assume a pressure of 20-100 psi - I'm not sure the maximum head on the Mag 7, but a head height of 20' only works out to about 10 psi. Also, aquarium pumps with their relatively minimal head-pressure are very affected by back-pressure, much more so than a typical pressurized system.

The chart I had was for (pressurized) irrigation. Pipe sizing also has a lot to do with distance. We just drilled a new well a couple months ago and it required 1 1/4" pipe for a 12 GPM flow.

 

[Weaksrt]

What best to do? Bush up at the pump given the pump is a smaller Diameter than what the Given flow should be? Say his pump is 3/4 discharge should he bush up to a 1" or even 1 1/4"? And if so should he use a hose and clamps all the way up and over the side? Or is putting a couple elbows up top to hang on the tank gonna matter?

 

[Dan F]

What best to do? Bush up at the pump given the pump is a smaller Diameter than what the Given flow should be? Say his pump is 3/4 discharge should he bush up to a 1" or even 1 1/4"? And if so should he use a hose and clamps all the way up and over the side? Or is putting a couple elbows up top to hang on the tank gonna matter?

What I would probably do is adapt to 1" flex pipe right at the pump (bushing and a 1" barbed fitting). Besides being easy to work with flex pipe helps isolate pump vibration/noise.

While PVC fittings do add to frictional losses it is minimal at the lower flow velocity you would get using 1" tubing. The smaller the pipe (and thus the higher the velocity) the more difference fittings will make.

Barbed fittings are a different story entirely - as they constrict flow in addition to changing directions they will suffer much higher frictional losses than PVC fittings of the same nominal size.

 

[Weaksrt]

Ok so no Barbed Elbows and such... Now is there Fx5 over the Tank wall parts that u can purchase seperately so no elbows are in the discharge? Do u know what i mean when i say Fx5 over the wall parts? If not its the part that makes the hose bend over teh tank wall and straps the hose to it... i think that would prolly be best and look cleaner than PVC and cause no friction loss or much added cost... (Looks like u knew what u were doing kinda thing)

 

[redtailshark1]

the bigger the pipe, the less pressure in the pipe the better