Fluval 305 and 404 Canister filter problems help please

[rnish]

I bought these 2 cannisters used a year ago.  They worked fine but intermittently one or both were incredibly hard to prime and start, needing the outlet to be put in a bucket below tank level.  They are filtering a 47 gal and a 77gal respectively and I need help desperately asap
the water changes are killing me....

Fluval 404:  Now I have difficulty getting a seal on the housing and the cannister.  IT takes many tries and leaks before it sits down right to seal.  The o ring looks in good shape but it takes an incredible pressure to close the cannister and it still leaks and has a visible crack. It almost feels like the media containers are in the way but I can't see anything wrong with them or the way they fit together. ( I have another 404 which this is not a problem once I learned to place it on the floor and lean my  body weight on it to seat the top housing.)

Fluval 305:  This one is running but the output is just a trickle, the tubing and canister are clean.  The impeller is straight blades.
Please help!
Jade

[dan2x38]

I've told many ppl to use plumbers silicone paste. NOT Soldering Flux! It is amazing it keeps the rubber from drying out, lubricates for pushing together the housing, and decreases clearance to prevent water leakage. Preston Hardware $4.99 enough to last a long time. I use it on all my rubber fittings. Also on all hose fittings it allows to easily remove them. This stuff is amazing makes handling a Fluval a breeze. I had a 303 for awhile.

[rnish]

 Thanks Dan!  I'll try it.
Any help for the 305??
Jade

[bergenm]

On the 305 my guess would be that either the impeller shaft or the impeller itself was not cleaned properly when it was last used - The impeller can not spin freely. Pull the impeller, clean it and the shaft.

There will also be a check ball in the intake strainer, make sure this moves freely.

Another possibility would be an obstruction in the hose. The hose might have been clear when you set it up, but any gunk in the hose will re-hydrate and can come loose and block the hose.

[rnish]

The 404 is going great now the grease is amazing stuff. tHANKS  AGAIN!
I'll try your suggestions for the 305 and get back to you .
Jade

[dan2x38]

I use the silicone on the shaft for the impeller. I hate the crinkled hoses a real trap for debris.

[rnish]

 Hey Dan and Bergenm
I got them both working!    Hurray my fish are much happier.
I was actually surprised how clean the crinkly hoses were.  When ever I restart the filters after a water change or a filter media clean I am always grossed out by the amount of gunk that gets spewed out of the outlet.  Yet the inside of the hoses don't have much gunk when I use my brush on them... Does the crinkle cause some sort of self clean on restart??
Thanks again for the support and help
Jade

[dan2x38]

What was the issue with the 305?