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temperamental cannister filter


handy-andy

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I have a Fluval 203 cannister filter. It's given me a good 10+ years service, but recently trying to restart it after cleaning has become extremely frustrating.

I clean out the filter media once a month, and the impeller and impeller well (and insert). Without fail after reassembling, it fails to restart. Water flows freely into the cannister, there don't appear to be any blockages - it just seems to have difficulty pumping water back up the 'out' tube to the spray bar. The motor makes a (barely audible) hum, so I suspect it's still working (assuming that most of the noise a working filter makes is attributable to the water flowing through it).

Eventually, after several attempts to disconnect, dissemble, reassemble and reconnect, the filter splutters back to life. The cause of this success is impossible to determine, as I haven't done anything different from all the preceeding unsuccessful attempts.

Most recently I gave it good whack (for scientific purposes of course!) and voila, it burst into life (though I'm sure I've tried this same method unsuccessfully in the past ;-) ).

Anyone experience similar problems? Did you figure out a solution?

Is it likely to be something as simple as trapped air that causes this, or could it be that the filter motor itself is nearing the end of it's days? Once the filter is working it runs trouble free until the next time I come to clean out the filter media.

If I have to replace the filter, what brand/model of cannister filter is recommended?

Appreciate any advice or shared experiences!

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We have 2 Fluval 404's and they are both difficult to restart. We went and got a couple of Jebo filters instead. They need cleaning less often (we have had ours 12 months and haven't cleaned them yet - water flow is still strong).

I seem to remember someone saying something about the outlet hose having to be above the waterline or something when you retart it.

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I don't usually have trouble with my fluvals anymore. If giving them a bit of a shake doesn't help just pull off the outlet hose and drain it into a bucket for a bit. That's usually more than enough to get it's throat cleared.

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It cause the impeller isn't turning. I think they are a shaded-pole permanent-magnet type motor. These motors have very low starting torque. As the motor ages, either the shaded pole piece has changed it's characteristic or the impeller has lost some of it's magnetism due to permanently being in an AC flux.

By banging it (experimentally) you are effectively giving the impeller a kick. There's a couple of things you can try:

1. Unplug and replug the power plug a few times until it starts (sometimes doesn't work). Depending when the power is put on during the mains cycle will change the starting torque a bit, maybe enough to start it.

2. Give it a whack!! It seems to have worked so far and it's a well-proven starting technique I used to use on mine regularly.

3. Do as Ira says, siphon start it. The force of the water going past the impeller starts it.

4. Buy a new impeller.

When you take it apart each time, you are putting the impeller back in a slightly different place. Sometimes you get it where it needs to be to start on it's own, sometimes not.

Fluvals also have quite small diameter rotors in their pumps, making them more prone to this problem.

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Thanks all for the advice. It's comforting to know it's not an unusual problem! Will persist with the 'percussive maintenance', and try siphon starting it next time.

I did investigate buying a new impeller - from memory it was about $80, and I thought that sounded a high price to pay without any assurance it would resolve the problem. I suspect it might make more sense to invest in a new filter if the problem persists. Those Jebo filters look reasonably priced by comparison to Fluvals or Eheims.

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