# Intake/Outflow Manifold-type Plumbing

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I'm finally setting up my 125 gallon tank, and because the aquarium divides two rooms and will be viewed from three sides, I'm going to run the plumbing beneath the substrate from one end of the tank to the other so that it will be completely invisible. (One end will be the "service" end, with plumbing in & out.) What I'm wondering is, if it is easier for a pump/filter to push the water through a long PVC pipe or to pull it through. Either way, I plan on having a larger diameter pipe to reduce resistance, but I just don't know if it makes a difference in flow rate. I'm also trying to decide if I should have a circular flow in the tank or one way from one end to the other. Another aspect I'm wondering if anyone has knowledge or experience with, is whether it is better to have all the water flow coming from one source at one end (or each end, opposite sides in the case of circular flow) to one return at the other end, or to have multiple outputs along the direction of current flow. And correct me if I'm wrong, but it occurs to me that connecting multiple pumps (I already have powerheads to use) to just one pipe would reduce the combined flow rate due to each pump adding back-pressure which the other pumps would have to overcome; thus, I suspect that a single pipe/hose dedicated to each pump would increase the overall flow rate; does anyone know if this is correct? I would like to hear about anyone's experience in this type of design.

Olskule
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1. Is it easier for a pump to push or pull water?

Depends where the pump is located, most pumps are designed to push water against gravity.

2. Larger diameter to reduce resistance.

Increasing the diameter may be beneficial on the intake if its flowing with gravity but has the opposite affect on the output if the output is going against gravity. You need to calculate for the extra weight/volume of more water that the pump has to push against height is a big factor here also. A pump can only push as much water through the pipe as there is room. Smaller creates the same problem of head pressure on the pump, you need to find that sweet spot. I'm sure there are calculators out there for this.

3. Circular flow

Only my opinion here but flow is flow and as long as its not creating dead spots your good. lots of factors involved like scape design, rocks and ornaments etc. all of which have the potential to create dead spots.

4. multiple pumps to 1 pipe.

Depends on pumps, head pressure, piping size etc. But what you stated makes sense to me.

To much math for me.

Dan
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1. Is it easier for a pump to push or pull water?<br />
<br />
Depends where the pump is located, most pumps are designed to push water against gravity.<br />
<br />
2. Larger diameter to reduce resistance.<br />
<br />
Increasing the diameter may be beneficial on the intake if its flowing with gravity but has the opposite affect on the output if the output is going against gravity. You need to calculate for the extra weight/volume of more water that the pump has to push against height is a big factor here also. A pump can only push as much water through the pipe as there is room. Smaller creates the same problem of head pressure on the pump, you need to find that sweet spot. I'm sure there are calculators out there for this.<br />
<br />
3. Circular flow<br />
<br />
Only my opinion here but flow is flow and as long as its not creating dead spots your good. lots of factors involved like scape design, rocks and ornaments etc. all of which have the potential to create dead spots.<br />
<br />
4. multiple pumps to 1 pipe.<br />
<br />
Depends on pumps, head pressure, piping size etc. But what you stated makes sense to me.<br />
<br />
To much math for me.<br />
<br />
Dan
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1: As for the application, I was thinking about powerheads used with piping within the tank to move the water from end to end, either pulling or pushing, depending upon which was more efficient.<br />
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2: In the same application described above, the water would be moving horizontally, so weight shouldn't be a factor. Incidentally, I had thought about using the principle you mentioned to help overcome the resistance of long piping on the intake side of the filter (below the aquarium) by using a 6" diameter PVC pipe placed vertically beside the aquarium, with reducers at the bottom to bring the size down to match the filter intake. I'm not sure how that would work, but I'm thinking that the column would have to be open or vented at the top (think extra-large overflow with syphons from the aquarium) to benefit from the atmospheric pressure/water's weight. But then, when I think about extending that "assumed principle" to eliminating the filter pump altogether, it becomes something of a perpetual motion machine, which, of course, is said to be "impossible". Hmmm. Needs some practical experimentation.<br />
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3: Flow direction: The 'scape I have in mind would lend itself to opposing flow directions​ on each long side.<br />
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4: Yeah, I think so, too.<br />
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Thanks for your thoughts. Maybe some of the engineering and math​ gurus will chime in with some facts, principles or equations.<br />
<br />
Olskule
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Are you going to plumb a sump? If so, will this design cause your plumbing's lowest point to be the bottom of the tank? Huge flood potential if so. For the water flow, 100% you want to push. I would also suggest using your return (pushed) water with several outlets to optimize tank flow.
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