Help me choose a return pump
- Thread starter Scott.h
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No, no, no. The calculation of loss is independent of the pump. The only difference is it's ability to over come the head loss. As you can see the Mag 24 has more loss than the Mag 18. Why? Not because of the line but because the Mag 24 had more pressure to lose. Yes the final calculation of flow and head loss will be different for each pump. However the fact that 1.25" has advantage over .75 PVC make no difference what pump you use, none!
Im not buying that theory, lets talk physics here. water flowing in a pipe has two zones so to speak, the center high flow and the outer part that is slower due to friction. the larger the line in a verticle, the more water weight you have against the impeller that is in addition to backpressure via diameter, elbows, valves etc. each pipe diameter size in sched 40 pvc is about 3lbs additional weight per 10 ft. the larger diameter you go the less velocity the water has to carry that weight.
So your saying the calculator that has been the back bone of reefing plumbing and return pump selection for more than 15 years has it all wrong?
Why don't you tell us all what the real flow should be?
What are you talking about?
The static back pressure from 10 meters of water in a pipe with 1 mm diameter is the same as it is at 10 meters depth in the ocean.
The weight of the water column does not affect the total flow from a pump - it’s only the sum of static and dynamic back pressure that matter. (what pro´s call pressure losses )
At the same pump height – the static backpressure is the same and independent of the pipe diameter.
However – the diameter of the pipe has a large effect on the dynamic back pressure – caused by the friction between water, water and the pipe. Generally – larger pipe diameter – lower dynamic back pressure. But there is a limit where you do not gain so much more flow that it is worth to have a larger pipe diameter. And because of the fact that the dynamic back pressure is caused by friction, bends and other obstacles rise the dynamic pressure from the interface of water, water and the inside of the pipe. I write water, water just to indicate that friction among water molecules also matter (laminar or turbulent flow matter for the friction)
My experiences are that for the DC pumps (low pressure pumps) – right pipe diameter is important for the flow and right diameter is often a larger diameter compared with pumps for higher pressure. For pumps with high pressure – the pump curve has a large importance for the choice of back pressure (can be manipulated by pump height or pipe diameter) - otherwise – the pump will cavitates
I think that the linked calculator is very good
Sincerely Lasse
Xclusive Reef
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I would get jebao dc 9000 or 12000. Super quiet pump.
mcarroll
10K Club member
Mag's do not require screwdrivers to start no matter how many times it gets repeated...and some folks seem to think DC pumps are perfect since they seem to get recommended in every pump thread and there's no realistic assessment of their features.
You can safely ignore anyone who thinks there is perfect equipment on the planet. Their advice will be misleading.
You can safely ignore anyone who thinks there is perfect equipment on the planet. Their advice will be misleading.
These are great if you are pumping from just under the tank, but I would not use these for a basement to another floor pump.
I would go with either a baldor motor reeflo, Iwaki, or a Little Giant external pump. All of these pumps are pressure rated and have been in use for the last 20 years with great success.
OP
OP
Scott.h
Valuable Member
Well I went ahead and redid my pluming this morning to 1 inch with a dual outlet. Here Is what it would look like now. Now I just have to pick a pump. I would assume with a 2 1/2 foot drop it would create somewhat of a vacuum that would help the flow also ..
mcarroll
10K Club member
A typical return flow rate would roughly match your skimmer...usually about 2x-4x your display size. (180-360 gph)
You are going to have more, better options at this flow rate. For example you could use an Eheim 1262 for about 300gph. Maybe the best pump ever made.
You are going to have more, better options at this flow rate. For example you could use an Eheim 1262 for about 300gph. Maybe the best pump ever made.
Breadman03
Valuable Member
I would still be using my Blueline 70 if it wasn't so stinking noisy! I suspect that heavy corrosion on the fan hardware from the previous owner is the culprit. I replaced it with a Red Dragon 230 which does the job silently while pulling slightly less current, though it is also moving a bit less water.
OP
OP
Scott.h
Valuable Member
actually I drilled my sump for a 1 inch bulkhead so I could do either or, potentially saving room and having a frag section in my return area. I built a shelf to hold the pump as well so at this point I would prefer an external. This is my second fuge build so I definitely learned always go bigger.
Breadman03
Valuable Member
More than I liked, but worth the noise.
The RD would compare favorably in a low head situation, but I'm using it in a basement sump which favors the Blueline heavily. My main reason-noise. It made my entire basement loud and the vibration could be heard and felt throughout my house. I could have done some work with padding and soft tubing, but decided to go with new and shiny.
The Blueline is now sitting on a shelf, just a couple of unions and plug away from being in service, should the need ever arise.
