External Filter Above Or Below?

[CorydorasBreeder'96]

Do you have to keep your external filter below your aquarium or is it OK to keep it above?

 

[fluttermoth]

External filters must be beloew the tank, as they work on a syphon principle (the water syphons into the filter and is then pumped back up to the tank).

 

[lock77]

Fluttermoth is 100% correct!

 

[fluttermoth]

Thank you Just a shame I can't spell 'below', really, isn't it?!

 

[lock77]

Thank you Just a shame I can't spell 'below', really, isn't it?!

Never even noticed!

 

[Prime Ordeal]

As long as the inlet and outlet are always below the water surface and there's no possibility of a leak in the hoses or connections, it's perfectly possible to run a cannister filter above the tank. You have to first prime the filter as normal below tank-level position and then lift it above the tank.

The slightest leak in a hose or in a seal in the cannister will however dump the contents of the cannister onto your nice floor and will then probably burn the motor out. Probably for this reason the manufacturer usually specifically says that you'll void your warranty if you operate it this way. Though I don't believe they'd actually be able to prove that's how it happened!

 

[steve1]

be hard to run a filter above the tank as there "gravity fed" it's like using a gravel hoover and trying too get it too work with a bucket above the tank the water just wont run lol

 

[Prime Ordeal]

be hard to run a filter above the tank as there "gravity fed" it's like using a gravel hoover and trying too get it too work with a bucket above the tank the water just wont run lol

Ok let me simplify it for you. Imagine you've got a length of clear hose pipe. You put it under the water until it is totally full of water. You then lift the middle of the hose pipe out of the water, and above the tank, but make sure that the ends always stay in the water. What happens to the water in the pipe?

Now you put a pump in the middle of the pipe without spilling a drop (you can do this because you're magic) and turn the pump on. What happens.

Simple physics mate (which you clearly don't have a grasp of)!

 

[steve1]

ok i dont have a grasp of physics why is that when you get an external filter does it tell you too have the item BELOW the tank so it will run it's gonna work a hell of a lot harder too suck water up over then it is down over this probably halving the age of the item and making it sound more noisey proabably as it's gonna be working alot harder.

now for a non pumped pipe try syphoning water from your tank up over and see how far you get if i dont know the laws of physic's sorry issac newton

 

[FarmboyUK]

Prime Ordeal is right. If there is no leaks and it is a completely closed system the pump will work above the tank.

You would have to prime it and get it running below the tank using the syphon effect and then you could lift it above the tank and it would keep pumping provided the motor stayed on.

 

[lock77]

FIGHT!!!!!!!!!!!

I'm with steve1, externals are not designed to work efficiently above water level! What is the point spending money on a good filter then destroying it cause you can't be bothered listening to the people who designed it!

http/www.youtube.com/watch?v=tbh3Ii7Qero&feature=player_embedded#!

2m 44s

 

[Prime Ordeal]

Steve has anyone ever told you that when you're in a hole you should stop digging?

why is that when you get an external filter does it tell you too have the item BELOW the tank

See my answer in post number 6

it's gonna work a hell of a lot harder too suck water up over then it is down over this probably halving the age of the item

Utter nonsense. I would use a stronger term but there's a swear filter.

Imagine the filter is fully primed and below the tank as the manufacturer recommends (i.e. as you would normally run an external filter). If you turn the pump off what happens to the water? Does it circulate? Does the water pour out of the filter outlet and back into the tank because of the 'syphon' effect?

The answer is that no it doesn't because the pressure difference either side of the pump is zero.

Now imagine the same filter above the tank, fully primed and ready to go. With the filter switched off what is the water doing? Answer, it's doing nothing because the pressure difference either side of the pump is zero.

What's the difference then between a filter placed an equal distance above the tank and below the tank? None in practical terms. When below the tank it has to 'blow' the water upwards into the tank. With the filter above the tank it has to 'suck' the water upwards to the pump.

The work done in both cases is the same and the pump is completely oblivious to its elevated position.


And, anyway, the question was, is it possible to run the filter above the tank, not whether it reduces filter life (which it won't)!

now for a non pumped pipe try syphoning water from your tank up over and see how far you get if i dont know the laws of physic's sorry issac newton

Dumbest statement I've seen on any forum in a long time!

FIGHT!!!!!!!!!!!

I'm with steve1, externals are not designed to work efficiently above water level!

Wrong. See my explanation above^^^^^^^^^^^^^

 

[lock77]

Steve has anyone ever told you that when you're in a hole you should stop digging?

why is that when you get an external filter does it tell you too have the item BELOW the tank

See my answer in post number 6

it's gonna work a hell of a lot harder too suck water up over then it is down over this probably halving the age of the item

Utter nonsense. I would use a stronger term but there's a swear filter.

Imagine the filter is fully primed and below the tank as the manufacturer recommends (i.e. as you would normally run an external filter). If you turn the pump off what happens to the water? Does it circulate? Does the water pour out of the filter outlet and back into the tank because of the 'syphon' effect?

The answer is that no it doesn't because the pressure difference either side of the pump is zero.

Now imagine the same filter above the tank, fully primed and ready to go. With the filter switched off what is the water doing? Answer, it's doing nothing because the pressure difference either side of the pump is zero.

What's the difference then between a filter placed an equal distance above the tank and below the tank? None in practical terms. When below the tank it has to 'blow' the water upwards into the tank. With the filter above the tank it has to 'suck' the water upwards to the pump.

The work done in both cases is the same and the pump is completely oblivious to its elevated position.


And, anyway, the question was, is it possible to run the filter above the tank, not whether it reduces filter life (which it won't)!

now for a non pumped pipe try syphoning water from your tank up over and see how far you get if i dont know the laws of physic's sorry issac newton

Dumbest statement I've seen on any forum in a long time!

FIGHT!!!!!!!!!!!

I'm with steve1, externals are not designed to work efficiently above water level!

Wrong. See my explanation above^^^^^^^^^^^^^

http/www.youtube.com/watch?v=tbh3Ii7Qero&feature=player_embedded#!
Your explanation hurt my head!

Is this a Fluval conspiracy?!?

 

[FarmboyUK]

Basically the filter will work above the tank assuming the inlet and outlet are always below the water level as this maintains a closed system with zero pressure

It will work but it is not practical in a world of regualar water changes etc.

Once the water level falls below the outlet the canister will empty it's contents back into the tank

 

[Bignose]

What's the difference then between a filter placed an equal distance above the tank and below the tank? None in practical terms.

Head pressure. Too low of a head pressure, and you risk cavitation which can destroy a pump very quickly. A pump below the water level will naturally have head pressure from the static pressure due to height difference. A pump above the water level will have negative static pressure, and will have to be primed in order to have the necessary head pressure for the pump to work correctly. Once the pump is primed, it isn't necessarily working any harder that it otherwise would, so long as that head pressure remains. Too low of head pressure and cavitation could occur, and the pump will be destroyed pretty quickly.