Canister Filter Positioning Question

[mark.w.jones]

I have a Fluval 203 canister filter at the moment running on a 4foot, 125 litre tank. Every couple of minutes at moment the flow rate really drops. Lots of bubbling noises go on the the canister. It then seems to catch up to full ouput flow again but blows out loads of bubbles for a bit through the spray bar. So far its never completely stopped but I'm a bit concerned about it.

Does this happpen because I don't have it below my tank?

At the moment it is sat right next to the tank on the tank stand. The tank stand is obviously longer than the tank, this was done on purpose to leave room for the canister beside. I would be a tad annoyed if I have to buy loads of new tubing and relocate the filter below the tank.

 

[vinylman]

It could be; now you mention it, I don't know whether externals HAVE to be below the tank. I suppose it helps with the flow OUT of the tank into the filter. On the other hand, it could be trapped pockets of air. Try shaking it side to side (rather than up and down) and see if it stops happening; if it stops, it was trapped air. Have you had the filter for long?. If so, how long has this been happening?.

 

[DevUK]

I have my 204 next to the tank and it occasionally blows bubbles, but not that often. Once its cleared the initial air pockets, its just occasional splutters. I usually tip it a bit to get as much air out as possible after I've cleaned it. I think the only thing is that its below the water line, even then its more to do with the syphoning to get it started. I have to hold mine below the tank to get the syphoning going again. Once running its fine.

 

[geo7x]

im sorry to say this but i think you have to have your filter below the tank, or at least that is the case with my eheim 2224.

If it is like my eheim then the tubing that goes into the filter is basically just like a siphon, its only the tubing going out of the filter that uses a pump to pump the water out and up, which leaves room for it to carry one siphoning in, creating a continuous circulation.

At least thats what my observation is

thats why you have to prime the filter to get it going.

 

[Teelie]

It should be kept below the tank. In the instructions, it should have a statement along the lines of no more or less than so many inches or feet below the aquarium it will be pumping water into and out of.

 

[mark.w.jones]

Cheers guys. All it says in the rather brief instructions is to keep the filter canister below the level of the water. This is rather ambiguous IMO. If as you say though the input pipe just works as a siphon then the fact that it keeps stopping would make sense as at the moment the end in the tank is below the top of my canister. It's gonna be a bit of a nitemare relocating it below but I will have to look do it I think. The tank is set up in the school I work at so I'm not around at weekends and don't want to return to disasters. Need to get some more tubing I feel.

 

[vinylman]

''Below Tank Level'' in the instructions would remove all doubt.

 

[DevUK]

As long as the top of the filter is below the water level it should be ok. You may find that you have to lower the filter to prime it (and get the syphoing going) but as long as its always below the water leve it should be fine

 

[mark.w.jones]

The problem is definitely with the input tube to the filter. Can anyone see any problem with moving the intake in the tank to nearer the surface in order to help with the siphoning or is it supposed to be near the substrate. At the moment the intake tube loops over the tank edge then right down vertically to just above the gravel. Could I twist this tube 90 degrees and have it running horizontally just below the water surface?

 

[Miss Wiggle]

the point with it being near the substrate is that it will pick up some of the waste that falls to the tank floor, now we all know you have to vac yourself but it would be significantly worse if the filter inlet was higher up in the tank.

however that coule be easily resolved by positioning a powerhead near the bottom of the tank blasting across a bit above the substrate towards the filter inlet, thus sending waste in that direction.

 

[Tolak]

Moving the intake tube closer to the surface won't make a difference in the strength of the siphon. This is determined by the surface level of the water.

 

[mark.w.jones]

Moving the intake tube closer to the surface won't make a difference in the strength of the siphon. This is determined by the surface level of the water.

Oh well you learn something new every day.

 

[mark.w.jones]

Well "Ye of Little Faith" Tolak . I twisted my intake pipe and strainer 90 degrees and suckered the strainer end about 2" below the surface of the water rather than 10" below on the bottom as it was. Lo and behold. No bubbling. No drop off of flow from the output spray bar any more. As Miss Wiggle said this is not ideal as most of the crap in a tank does not congrigate 2" below the surface but at least my filter no longer seems in danger of having the water flow completely stop anymore. Will just have to gravel vac more often to compensate.

 

[Tolak]

Well "Ye of Little Faith" Tolak . I twisted my intake pipe and strainer 90 degrees and suckered the strainer end about 2" below the surface of the water rather than 10" below on the bottom as it was. Lo and behold. No bubbling. No drop off of flow from the output spray bar any more. As Miss Wiggle said this is not ideal as most of the crap in a tank does not congrigate 2" below the surface but at least my filter no longer seems in danger of having the water flow completely stop anymore. Will just have to gravel vac more often to compensate.

Get out. I'm going to have to mess with some of my canisters tonight to see if there is any flow difference. I know for a fact from siphoning tanks that the depth of the end of a siphon in a tank doesn't affect the water flow rate, but the water level will.

 

[Miss Wiggle]

see who needs the laws of physics!! lol