# Fluval 306 Aqua-Stop valve won't fit



## hivemindhermit (Oct 19, 2017)

Believe it or not, I have a 06-line Fluval canister and my issue is NOT priming! Rather, I tried to set it up yesterday, and when I tried to attach the Aqua-Stop valve, the locking lever broke off. To me it seems like the valve simply won't fit into the canister; it's impossible to push it down so that it's flush with the top of the canister. Which means the locking lever can't actually lock, so when I applied force, instead of snapping the thing into place it just snapped off. 

The weird thing is I bought this filter used, and it has clearly functioned before. So... What gives? Anyone else had this happen? Will replacing the valve fix it or will I have to replace the whole thing? 

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## Angelo3658 (Jul 28, 2018)

I have a Fluval 406 with the same issue. Bought used was working and now can’t get the valves to lock back in place. Haven’t broken the lever...yet! Have you found a solution?


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## gus6464 (Dec 19, 2011)

You need to lube the o-rings. Use scuba safe silicone lube.


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## PlantedRich (Jul 21, 2010)

I saw this post but passed it by, seeing it again today prompted me to dig out the old 306 parts and take a look. I think Gus6464 may have the correct diagnostic but I would suggest a different fix as being easier for many of us. 
The connecting block on my old junker has dried somewhat and the block would not fit down into the head without a good deal of force but I think lubing the O-rings is the first step for cure. This is where I might differ from Gus as I find petroleum jelly (Vasoline?) without the menthol is the best lube I find. It is simple and easy for me as we keep it for a number of things. It is also fish safe and recommended in some of the Eheim manuals! 
What I find on my Fluval head is that the o-rings need to be lubed so that they will slip down into head without me needing to force them. Once fully seated, the red lever can then be pressed down to lock the block into place and then the white lever for the water cutoff can be turned to open the tubing. Would not be a bad idea to smear just a bit of lube on the notch in the red plastic as well as just a touch on the tip of a Q-tip worked up inside the openings to lube the cutoff ball valves. 
Not to get crazy with the lube but just smear on and wipe it off to leave a sheen of lube left is better than a whole bunch. 
See if that doesn't let things move as they should. I'm guessing what happens is the block and O-rings are a bit stuck in the head and we can break the red lever by pulling too hard while it is stuck.


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