Some help please? Can't get Fluval 406 to prime

[elbereth]

I bought a Fluval 406 filter used. It was pumping water just fine before the previous owner dismantled it. Now I can't get it to prime even after filling the canister and hoses. There are two problems from what I can tell:

1) The impeller is seizing up. First it rattles as if it's working in air even with the canister being full. I tried tilting and shaking to "burp" the filter in case there's air trapped inside but the impeller keeps rattling and then stops spinning. The impeller looks perfectly fine though and I cleaned the filter thoroughly so it's not getting stuck because of gunk.
2) The canister seems to leak a bit even though the lid forms such a tight seal I have trouble prying the lid off sometimes.

Any advice or tips would be much appreciated. Thanks in advance!

 

[James.Lafontaine]

I would just buy a new impeller for it. they're like $20 on amazon and if it doesn't work you can always return it. and for the leak I would rotate the base of the canister because my filstar XP filter doesn't sit right and leaks unless I turn the base 180 degrees and then it doesn't leak.

 

[elbereth]

Thanks for responding! I guess I'll try a new impeller.
When you say your filter doesn't sit right unless you rotate it do you mean something to do with the angle of the hoses? I never thought of that!

 

[James.Lafontaine]

Lol disregard what I said about my filter because yours is completely different. I would also get a new motor head gasket or a gasket that fits between wherever it’s leaking. Sometimes the gaskets go bad or they dry out due to inactivity

 

[Oughtsix]

I had a Fluval 404 and it left me with a bad taste about Fluval filters. You have to have the filter packed perfectly so the top sits tight on the lower housing. If you have a leak you don't have it together properly. A tiny piece of bio media, activated carbon or tiny pebble of gravel will mess up the stack of trays and keep the top from sealing properly.

My 404 was never easy to prime. The best thing to do is put the output hose into a 5 gal bucket on the floor instead of back into the tank which should give your a water level differential to create a self sustaining siphon on its own. Give the output hose a good suck, put it in the 5g bucket, then turn on the filter. Once you have continuous flow into the bucket you should be able to unplug the filter, transfer the output hose into the aquarium, plug it back in and it should work properly.

Once the 406 is sealed well, doesn't leak, is primed and running it should do its job just fine. It is just that the Fluval 404 and related filters in the same family seem to need a lot more messing around with to get them sealed, primed and running than some other high end canisters.

 

[elbereth]

Reviving this old thread. It's been a very stressful past few months and I only recently got around to buying a new impeller for this filter. Still can't get it to prime. I'm really bummed because if I can't really afford to buy another filter now. ☹ Anyone else have any ideas what might be wrong?

 

[elbereth]

Oughtsix, just saw your recommendations from way back when. I actually can't get the lid to sit perfectly flush with the bottom of the canister because the O ring is in the way if that makes any sense. Also the output hoses don't sit absolutely flush with the lid though they lock in place so I guess it's possible the canister is sucking in air somewhere around there. Such a pain.

 

[mnloki]

Could you get a picture of where the o ring sits? Are you positive it is seated correctly?

 

[elbereth]

Sorry, I looked at it again and it's not the O ring specifically (that's sitting correctly) so much as the whole underside of the lid. I can't push the lid down all the way so I get a gap 4 or 5mm wide as in the picture. I tried removing the media containers even - same problem - so it's not them that are in the way.

 

[aotechs]

I had one of these filters on a tank in the past. I had the same sealing and priming issues that you are running into here. My advice is to keep opening and closing the lid until it sits even and make sure not to pinch the seal. To prime, lift the output hose above the aquarium and pour water into the output hose until all air is pushed out the intake.