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Problem With Eheim(S) In A Drilled Tank(S)


Lordoftheswarms
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Eheim 2026

Ecco pro 2236 (this is the only one I tried in the configuration I have in mind)

and another that I don't have the model number for.

First of all, all three Eheims work if they go over the tank lip.

I am not wanting to have the filter like that though. I would like my tanks to be drilled on the bottom instead.

Both the intake and the outtake are drilled.

It hasn't worked for me in that configuration despite several attempts. What am I doing wrong?

The water is draining, the drain into the intake isn't plugged. But water doesn't want to move up the outtake.

The self priming gets the water up, but it doesn't move beyond that.

Can Eheim filters work in drilled tanks? If not, which filters would work in this configuration?

Thank you for your responses.

Edited by Lordoftheswarms
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Is it sucking air at any point along the line?

I'd assume not as you said nothing about little water leaks

Or perhaps, it isn't powerful enough for that height. If this...maybe throw books underneath until you find a height that does work and go from there.

dunno, just trying to help with spitballing. :)

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Do you have a pipe for the outtake or is it plumbed to output at the bottom of the tank? If you don't have a pipe, the height of the water is creating a back pressure that the pump cannot over come.

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Both the intake and the outtake are drilled.

So both suction and discharge is plumbed through your tank bottom.

There is a pipe for the outtake going fairly high.

... and your discharge is higher than your suction.

Ok. I'll ask: Are you sure the discharge end (your outtake pipe) is actually connected to the OUT connector on your canister?

Edited by Fisher
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I think pics are in order because I'm sure I've seen Eheims used in drilled systems, and have seen other canisters used that way for sure.

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I am sure that most canister filters will never be able to overcome the water pressure in a hose plumbed into the bottom of a tank. The outlet side of the canister should be plumbed into the side of the tank somewhere or you could plumb from the bulkhed on the inside bottom of the tank to closer to the top with pvc so the canister does not have to overcome all that water pressure,

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I dusted off my old IPT hydraulics theory handbook before replying. All the laws of physics and practice are acting in your favor. Remember the ol water towers? In a tank that’s open to atmosphere, water will impose a force of 0.433 psi per vertical foot regardless of tank volume (I know it sounds counterintuitive). It dosen't matter if the inlet/outlet pipes rise from the bottom of your tank, or if it drops down from the outside. What matters is where in the water column your pipes end.

So the water weight above your suction end will assist your pump; the deeper the suction end is in your tank, the more water pressure acting on your pump's inlet side. If your suction ends one foot below the water column, there's 0.433 psi acting on the suction side.

The water weight above your discharge end will resist the pressure generated by your pump; the deeper your discharge is in your tank, the more water presure acting on your pump's outlet end. If your discharge is 3” below water level, the “back” pressure your pump will have to overcome is 0.108 psi.

So having a discharge higher than the suction creates an advantage for the pump… which happens to be the classic arrangement for canister filters.

With all valves open, no air lock and no plugged lines, and power to the pump, water should flow.

You can try generating a flow pulse in the discharge side to see if that motivates the water to move. A troubleshooting technique an old salty millwright once taught me: Simply pressure up the discharge side by partially closing the outlet valve while the pump runs. Then open the discharge valve fully to generate a flow pulse. It might be enough to get water flow.

You can reconnect your canister dry, let the siphon fill it and use the water flow inertia to start the same procedure above.

When there's a pressure differential, there will be flow.

Edited by Fisher
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So what I'm gathering is you want to have the drain low in the tank and the return run up closer towards the surface.

Personally I wouldn't have pipes that were less than 3/4 the height of the tank. Any lower than that and I'm actually surprised you don't have water spraying out around the filter seal. I bet if you removed the hose from the bulkhead and tried to plug it with, say your hand, while you filled the tank I bet you wouldn't even come close to being able to keep a seal.

I lost my balance the other day while servicing under my tank (okay, I was trying to plug in a tv to the powerbar) and I straight up knocked the return hose from my FX5 off the splitter (extravagant plumbing setup) and water started shooting from three directions. I had to get my gf to turn off the filter, pull the return out of the water (to stop the gravity feed), turn off a valve (to stop the gravity feed from the filter intake) turn off another valve to finally stop all water flow from the filter/uv. I used my thumb to plug the return that was at the time back syphoning and it took everything I had to keep it plugged.

I think I was crying, laughing and straight up freaking out all at the same time.

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