Pulling water uphill with a return pump?

[Swingline77]

For the common return pumps (Eheim, Danner, Iwaki, etc.) I see "head ratings". It's my understanding that this rating refers to the height to which a pump can push water. What if I want to pull water uphill, though? If a return pump has a head rating of 5 ft, could I have the pump at the height where I want to water to exit, and pull it up from 3 or 4 (or a theoretical maximum of 5) feet below?

 

[LobsterOfJustice]

None of these standard pumps can pull water when there is air in the line. If you have some way of priming the plumbing to remove all air, it will work, but it really isn’t what the pumps are meant for.

 

[mcarroll]

Special situation you're installing into, or just a general pump question?

 

[KrisReef]

The theoretical head pressure of a pump 5’ above the tank is -5’ . Running without water, the typical hobby pump will not create suction in air, so the water level will remain at 5 feet below the pump.
If you flood the pump and the 5’ of intake line intake with water (prime the pump) the hobby pump rated at 5’ of head pressure can draw water up 5’, but since you are working against -5’ already the output of the pump will theoretically be zero.

So if you want to have a flow at five feet of head drawing pressure you will need a pump that actually produces greater than 5’ of “head pressure” and a flooded intake system into the pump before the pump is switched on.

 

[Swingline77]

Special situation you're installing into, or just a general pump question?

General question

 

[Swingline77]

The theoretical head pressure of a pump 5’ above the tank is -5’ . Running without water, the typical hobby pump will not create suction in air, so the water level will remain at 5 feet below the pump.
If you flood the pump and the 5’ of intake line intake with water (prime the pump) the hobby pump rated at 5’ of head pressure can draw water up 5’, but since you are working against -5’ already the output of the pump will theoretically be zero.

So if you want to have a flow at five feet of head drawing pressure you will need a pump that actually produces greater than 5’ of “head pressure” and a flooded intake system into the pump before the pump is switched on.

OK, thanks.

 

[laverda]

Most of the pumps we use do not work well or at all if not below the sump water level. Even 1 foot higher most will not pump anything with out being primed.

 

[ca1ore]

Yeah, you'd have to use a priming 'basket' ..... even then I'm not sure how much above the water one would work.

 

[mattgsa]

The pumps used for pools self prime, however, I don't know of any for aquariums that are self priming.

 

[WVNed]

Water is a liquid. You cant "pull it"

It simply flows from an area of higher pressure to one of a lower pressure.