External Above Tank?

[RadaR]

Hey. I want to put a second hand Fluval 204 above my 3ft tank as there is no where else it can go on the ground. I seem to recall at some point, hearing that externals shouldn't be placed above the tank, is that true?
Also, the Fluval 204 came with ribbed hosing, which I don't like at all, so can I just use normal piping on it like on the Eheims? (providing it's the same diameter of course).

 

[DevUK]

First question, not really. Externals rely on gravity to get the syphoning going, so you would have major problems priming the filter, unless you had it below the tank when you fired it up and then moved it after. Even then I think you would have problems in the long run. I'm not 100% (maybe someone else can comment) but I think it would put the motor in the filter under a bit more stress. You might find it gulping now and then. I ran a 204 sitting next to a tank. I had to move it below the tank to get it primed (though, one of the hoses was far too long and needed trimming ideally), it ran OK sitting next to the tank though, with the occasional burp.

Second question, yes. I have replaced the tubing on one of my 204s with Eheim 16/22mm tubing. It fits directly onto the taps on the filter, but I found I needed to use the Eheim spraybar/inlet kit (could use another brand but this was all I could get hold of). The Fluval inlet/outlet fitted with a little persuation, but I couldn't get the tubing into my tank without kinking it, unlike the ribbed hose. Using the Eheim parts with the plastic tank overhangs fixed this issue (managed to get them cheapish from LFS too)

Will post pics if you'd like to see but it really is a case of screwing the hoses on as you would the rubber end gromits on the fluval pipes.

 

[Colin_T]

external canister filters work on gravity draining water from the tank into the filter. Then because the filter is a sealed unit the water fills up the filter and goes back up through the return/ outlet hose. The pump only has to push the water up over the edge of the tank.

You can have the filter next to the tank as long as it's slightly lower than the water level.
If you have the filter above the tank it won't work.
The only way to get the filter to work above the tank would be to have a seperate pump in the tank that pumps water up to the filter and then it can drain through the filter and back into the tank.


You can use any sort of plastic hose (Eheim hose) for the filter. Just get some that fits onto the filter.

 

[RadaR]

Ah ok, that's a no go then. Atleast I can get some different tubing though.
Really appreciate the replies you two, you hit the nail on the head.
Thanks again.

 

[Rooster]

I'm going to play Devil's advocate here, and think aloud ! Externals are a closed loop with a pump, once its primed it 'SHOULD' work at any height, not got a spare to try the theory though...

Only danger I can see is that the outlet syphons dry... bad news for the pump, but if the outlet were under water at tank end it should be fine. (or put an upward loop in outlet pipe, to create a wier)

Thoughts please ?