Fluval 305 External Filter Problems

[jimmyjazz1039]

Hi so I've set up my new 240L Fluval Roma tank and I'm having trouble with the 305 external filter.

I know it works as I can see bubbles coming out of it when I move it around but whenever I just leave it there the bubbles stop and it doesn't work anymore. The only thing I can think of is that the tubes connecting it don't sit staright and go all bendy but that doesn't seem to be the problem as when I'm moving it the tubes stay bendy.

I've never used an external filter before, does anyone know how to solve this problem? The guide that came with it offers no assistance whatsoever!

[markart]

Are you sure that the outlet hasn't just dipped below water level and isn't disrupting the surface?

[jimmyjazz1039]

The outlet is definatley below the wtaer surface, should this not be the case? My dad seems to think that bubbles should not be being produced, but as I say I have no idea on external filters right now. I can feel a flow being produced by the outlet, but definatley no bubbles.

So should bubbles be being produced?

[markart]

Ideally the outlet should disturb the water surface to aid gas exchange, this may or may not produce some bubbles. I think you are thinking of a Venturi effect normally found/suppled with internal filters which sends lots of small bubbles into the water. They aren't really necessary and are supplied to put more Oxygen into the water, but this isn't an effective way to do this anyway.

[jimmyjazz1039]

Ok thanks, so as long as there is a water flow the filter is set up correctly?

[markart]

Yes.

[jimmyjazz1039]

Righto, cheers dude

[Hague1982]

bought a 305 myself this week and the DVD instructions are useless! the reason there are no bubbles is that it tells you to place the outlet 3inch below the surface of the water as to agitate the water, i have mine running with a Fluval U4 internal as well and i have that nearer the surface to create more ripples in the water but there defo should be no bubbles if there was bubbles it was air coming out of the filter

[BigBlackMoor]

It shouldn't matter where the output is, it makes no difference to the performance of the filter.

It should be pumping so hard that the output nozzle will literally wobble as the water forces out.

Can you verify that you have put your hand in front of the output nozzle & that you can feel the water coming out?

Air will only escape from the filter after maintenance. Once wobbled about a few times & rocked from side to side, it will soon dissipate.

Did you cut the hoses to length as described in the installation DVD?

There ideally, should be no kinks or loops in the hosing & it's important that the canister is mounted as per instructions when it comes to height of tank. It's vacuum fed, it does not pump water "into" the canister, only "out" if that makes sense. It relies on the constant syphon effect.

Please post back if you are having problems still as your stock is at risk if the filter is not functioning correctly.