# canister filter low water level



## JEFF9922 (May 8, 2013)

I have a 20g high that I will only have below half full of water . I am wanting to use a small 106 gph canister filter but am worried it won't pull up the water . Anyone have experience with this?


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## Willcooper (May 31, 2015)

It will pull it up fine. Most canister filter intakes are pulling from the bottom of the aquarium anyway. The return is what you need to pay attention to. Check the maximum head height of the return pump and place accordingly


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## DaveK (Jul 10, 2010)

The canister will move the water, but since your intake is below the level of where you'll be returning the water, you will experience some loss of flow. This is usually ok, as long as you are aware of it.


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## PlantedRich (Jul 21, 2010)

You are correct to question this. The filter works much the same as a siphon with a motor added to boost the flow over the edge. The point at which the water is picked up is not the main factor but the water level in the tank. Just the same as with a siphon. 
How much it will reduce the flow and whether it will work is a hard one to guess as there are so many different things to effect the flow. I might guess that it will not restart but then that is just a GUESS!


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## AndreyT (Apr 28, 2011)

JEFF9922 said:


> I have a 20g high that I will only have below half full of water . I am wanting to use a small 106 gph canister filter but am worried it won't pull up the water . Anyone have experience with this?


Canister filters do not really have to "pull" anything anywhere. As long as your intake and outflow are submerged under tank water level and the system is fully primed, your canister filter remains a sealed bypass system that does not know anything about gravity. It does not work against gravity, regardless of how low the tank water level is. Also, it does not matter where the canister itself is located (below, next, above the tank).

However, this only applies when your outflow nozzle is submerged. Is it? If your outflow is above the tank water level (any kind of "waterfall" outflow or a spraybar), then your canister filter pump will have to do some work against gravity. The greater is the height of the "waterfall", the more work it will have to do.

But you haven't provided any information about your outflow. What is it going to look like? Are you planning to keep it submerged?


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## JEFF9922 (May 8, 2013)

Out flow will be submerged and lower then intake .


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## PlantedRich (Jul 21, 2010)

That changes the whole setup and it will be likely to work. Devil in the details type thing! That returns it to a simple siphon situation.


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## AndreyT (Apr 28, 2011)

JEFF9922 said:


> Out flow will be submerged and lower then intake .


In that case you are perfectly fine. 

The only situations that might pose some difficulties with that setup is when your filter is not yet primed (i.e the hoses are empty) and you have to prime it. In this case you will actually have to somehow pull/suck the water into the intake hose to make it go over the edge of the tank. (Assuming your hoses are routed over the edge of the tank.)


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