# Intermittent air lock issues with Fluval 406



## keymastr (May 25, 2015)

It is the main o-ring where the motor assembly mates to the media section. Mine does the same thing about every third cleaning and I replace the o-ring after that. Sometimes you can see a slight leak down the side as well.

You can try cleaning the o-ring and channel that it sits in and then lubricate it with some mineral oil before putting it back together. That works about half of the time.

Bump: I found O-rings on Amazon for $10 for 5 of them. Cheap insurance so I always keep them handy.


----------



## Zoomy (Sep 13, 2014)

I wondered if that were the issue...though I haven't seen any signs of leaking water, so I thought maybe a different leak were to blame. I have to run to Petsmart for some odds-n-ends, so I may grab a new O-ring and replace it when I do a water change tomorrow. Sheesh, this filter is only maybe 5-6ish weeks old. At the very least I'll pull it off and give that area a good cleaning and lube the o-ring, though it's been doing this since day 1, IIRC, so I wouldn't think grime would be the issue.

Another possibility...the intake is near the Co2 diffuser. Maybe 6" apart and the diffuser is slightly lower than the bottom of the intake. Is it possible that it's a build-up of Co2 bubbles? It doesn't look like very many bubbles are making their way into the intake, but perhaps enough to build-up the bursts of bubbles...?


----------



## pinsonja (Jul 7, 2015)

I have this exact same problem. my Nat Geo cf 80 did this right out of the box .

Sent from my SM-G900P using Tapatalk


----------



## Zoomy (Sep 13, 2014)

pinsonja said:


> I have this exact same problem. my Nat Geo cf 80 did this right out of the box .


It's sort of reassuring knowing that different brands do this same damned thing. :tongue: I can totally live with it if I know that it's not going to get worse and/or cause any serious damage to the pump. But it does make me sorta wish I'd gone with the Eheim 2217. I was really flipping a quarter over which filter to get and went with the Fluval because what I'd read suggested that it's easier to prime and clean and I do like the filter baskets. But if I get fed-up I may shove the Fluval in a closet as an emergency back-up and go with the Eheim, anyhow.


----------



## pinsonja (Jul 7, 2015)

Zoomy said:


> It's sort of reassuring knowing that different brands do this same damned thing. :tongue: I can totally live with it if I know that it's not going to get worse and/or cause any serious damage to the pump. But it does make me sorta wish I'd gone with the Eheim 2217. I was really flipping a quarter over which filter to get and went with the Fluval because what I'd read suggested that it's easier to prime and clean and I do like the filter baskets. But if I get fed-up I may shove the Fluval in a closet as an emergency back-up and go with the Eheim, anyhow.


I'm not sure exactly how much damage yours will do. With mine, if it starts pushing too many bubbles, the motor starts knocking and fumbling around and I have to re-prime it. I've never had a fluval but now that I know how much of a junk brand Nat Geo is, ill most likely be giving in to a fluval in the near future. I don't just knock brands over one product, I also have a Nat Geo 50 powerhead that likes to just stop whenever it feels necessary. That's how I know this brand is junk. 

Sent from my SM-G900P using Tapatalk


----------



## Zoomy (Sep 13, 2014)

pinsonja said:


> I'm not sure exactly how much damage yours will do. With mine, if it starts pushing too many bubbles, the motor starts knocking and fumbling around and I have to re-prime it. I've never had a fluval but now that I know how much of a junk brand Nat Geo is, ill most likely be giving in to a fluval in the near future. I don't just knock brands over one product, I also have a Nat Geo 50 powerhead that likes to just stop whenever it feels necessary. That's how I know this brand is junk.


I'm not sure, but I thought I read that the NG filters are actually Eheim Ecco units...but I also think I read some mixed reviews of the actual Eheim branded ones, too. Seems like the Eheim classics are the ones that get the really glowing reviews, but the rest are pretty meh.

At least on Amazon the brand that has me intrigued is Penn Plax...their Cascade line seem to get some really great reviews and the price isn't bad. I'm sorta intrigued by those, but I don't really see any chatter here about them, which gave me pause when I was first looking at filter options.


----------



## pinsonja (Jul 7, 2015)

Zoomy said:


> I'm not sure, but I thought I read that the NG filters are actually Eheim Ecco units...but I also think I read some mixed reviews of the actual Eheim branded ones, too. Seems like the Eheim classics are the ones that get the really glowing reviews, but the rest are pretty meh.
> 
> At least on Amazon the brand that has me intrigued is Penn Plax...their Cascade line seem to get some really great reviews and the price isn't bad. I'm sorta intrigued by those, but I don't really see any chatter here about them, which gave me pause when I was first looking at filter options.


You're right, I've read some really great reviews about the Eheim classics. As for the Penn Plax Cascade, I have my Cascade 700 on a 55 gallon and it certainly gets the job done. I wish it had stronger flow so I could eliminate a powerhead but overall for me it's a 5/5. It's inexpensive, very quite, easy to clean and easy to prime. I'd recommend it to anyone. 

Sent from my SM-G900P using Tapatalk


----------



## Zoomy (Sep 13, 2014)

pinsonja said:


> You're right, I've read some really great reviews about the Eheim classics. As for the Penn Plax Cascade, I have my Cascade 700 on a 55 gallon and it certainly gets the job done. I wish it had stronger flow so I could eliminate a powerhead but overall for me it's a 5/5. It's inexpensive, very quite, easy to clean and easy to prime. I'd recommend it to anyone.


Very interesting. I was looking at the 1000 as a potential future option for my 50g. I have 2 circulation pumps with my Fluval, so even if flow were an option I'd be OK with that, so long as the filter actually did a good job removing crud. I like the easy to clean and easy to prime features. Those are the things that tipped me in favor of the Fluval over the Eheim Classic, in the first place.


----------



## keymastr (May 25, 2015)

I believe NatGeo is the cheapo brand that Walmart carries with the Nat Geo name on it. As for the O-ring I would not worry about it hurting anything. Once when I was out of O-rings mine burped air for about a week, every 30 seconds. 

I would doubt that it is the co2 bubbles. It would take an awful lot of them and you would see and hear a constant amount of them being chopped up by the impeller. If it has done it since day one then most likely the O-ring is just not seated properly or there is something else preventing the top section from sitting down fully. Try lubricating the O-ring and see if that helps. My filter is several years old and other than the O-ring there has never been any trouble. Great filters in my opinion.


----------



## Zoomy (Sep 13, 2014)

Yeah, I'm going to clean and relube and see if that helps. How do you clean the channel...wet q-tip?


----------



## keymastr (May 25, 2015)

Or just cram some paper towel in there and wipe it out. It cleans very easy.

If that does not fix it you can contact Fluval and have them send you a new O-ring since it has been doing it since day 1. The other possibility is that the priming valve is leaking. I have heard of those failing although I have never seen it myself. I think those leak water when they fail though. The O-rings always suck air, just like yours is doing and when you unplug the pump you should see a trickle of water running down the side. You might just unplug it for a minute without touching any of the valves to see if it leaks. That would confirm the O-ring.


----------



## Zoomy (Sep 13, 2014)

I gave my filter an extra good cleaning today (replaced 2 of the 4 tall foam blocks -- would have replaced all 4, but I didn't realize I only had 1 2-pack -- and the polishing pads). Removed the o-ring, wiped it really clean, wiped the channel it sits in clean, then slathered-on some silicone grease. I also gave the intake strainer/ball assembly a good cleaning and brushed-out the intake tube that it attaches to. So far it seems to have minimized the # of air lock bursts, but there are still a few, here and there. Kind of annoying, but I'm thinking this is just the way the filter's going to run.

Also, how in the world do so many of those dumb bladder snails end up thriving in my filter? Dummies are finding their way into the intake. And then they go and lay eggs inside the filter. Yuck. If I didn't like my nerite snails so much I'd get some loaches or something to eat them. I'm hoping maybe my ghost shrimp or dwarf crayfish will get a taste for snails. Some do, but I haven't seen any snail snacking...yet.

Bump:


keymastr said:


> The O-rings always suck air, just like yours is doing and when you unplug the pump you should see a trickle of water running down the side. You might just unplug it for a minute without touching any of the valves to see if it leaks. That would confirm the O-ring.


I'm going to have to experiment with that to see if there's any leak. I did wonder about the primer, too, but haven't seen any leakage in that area, either.


----------



## Zoomy (Sep 13, 2014)

Update: Almost 24 hours since cleaning and re-greasing the gasket and it's utterly silent. No more regular spurts of bubbles. Right out of the package it appears the O-ring wasn't greased enough, perhaps. I'm definitely going to pick up a back-up gasket, since this appears to be a weak point in the Fluval filter design.


----------



## keymastr (May 25, 2015)

Glad it settled in. They are a great filter but that does seem to be their one flaw.


----------



## pinsonja (Jul 7, 2015)

Zoomy said:


> Update: Almost 24 hours since cleaning and re-greasing the gasket and it's utterly silent. No more regular spurts of bubbles. Right out of the package it appears the O-ring wasn't greased enough, perhaps. I'm definitely going to pick up a back-up gasket, since this appears to be a weak point in the Fluval filter design.


Glad to hear it worked. I'm going to try this with my NatGeo. What did you use? 

Sent from my SM-G900P using Tapatalk


----------



## Zoomy (Sep 13, 2014)

pinsonja said:


> Glad to hear it worked. I'm going to try this with my NatGeo. What did you use?


In the plumbing section at Home Depot there are 2 tiny tubs of grease. One says waterproof grease, the other says silicone. I wasn't sure what was in the waterproof one, but knew that silicone is recommended for the Fluval o-ring, so I grabbed that. It's similar in consistency to spun honey.


----------



## AndreyT (Apr 28, 2011)

Zoomy said:


> So...about every 5-10 min or so (haven't timed it, but this is my best guesstimate) my filter will spit out a bunch of bubbles for a couple seconds -- not a huge amount, but I'm under the impression that it shouldn't be releasing any bubbles at all if the entire system has a proper seal.


With canister filter, if the system is not sealed it will constantly leak water. No way around it. Does your filter leak water?

If your filter does not leak water, then the air you observe cannot possibly come from outside (unless you are feeding air into the intake tube opening somehow). If your filter does not leak water, then whatever burping you observe is just an isolated air pocket trapped in the filter after previous maintenance. It should dissipate eventually, at which point the burping will stop.

The idea that impeller pump in a typical canister filter has enough power to suck air from outside is highly questionable. Moreover, the idea that impeller pump can suck air thorough an opening _at canister level_ (where the inner water pressure is the highest) is flat out preposterous.


----------



## pinsonja (Jul 7, 2015)

Zoomy said:


> In the plumbing section at Home Depot there are 2 tiny tubs of grease. One says waterproof grease, the other says silicone. I wasn't sure what was in the waterproof one, but knew that silicone is recommended for the Fluval o-ring, so I grabbed that. It's similar in consistency to spun honey.


Ok thanks, we'll see how this goes. Hopefully my luck is as good as yours. 

Sent from my SM-G900P using Tapatalk


----------



## pinsonja (Jul 7, 2015)

Zoomy said:


> In the plumbing section at Home Depot there are 2 tiny tubs of grease. One says waterproof grease, the other says silicone. I wasn't sure what was in the waterproof one, but knew that silicone is recommended for the Fluval o-ring, so I grabbed that. It's similar in consistency to spun honey.


I'm not sure that the home Depot near me carries what you have. The only thing I see is plumbers grease. Do you think that would work?

Sent from my SM-G900P using Tapatalk


----------



## Zoomy (Sep 13, 2014)

pinsonja said:


> I'm not sure that the home Depot near me carries what you have. The only thing I see is plumbers grease. Do you think that would work?


I would think so. My guess is anything related to plumbing wouldn't be toxic. Some people use vaseline, though I've seen mixed recommendations with that.


----------



## pinsonja (Jul 7, 2015)

Zoomy said:


> I would think so. My guess is anything related to plumbing wouldn't be toxic. Some people use vaseline, though I've seen mixed recommendations with that.


I was wondering about that as well. Either that or petroleum jelly? 

Sent from my SM-G900P using Tapatalk


----------



## Zoomy (Sep 13, 2014)

pinsonja said:


> I was wondering about that as well. Either that or petroleum jelly?


Yup.


----------



## pinsonja (Jul 7, 2015)

Zoomy said:


> Yup.


Apparently my luck isn't as good as yours, it didn't work. Going to an Eheim classic. Thanks for the information though, much appreciated. 

Sent from my SM-G900P using Tapatalk


----------



## oldpunk78 (Nov 1, 2008)

Every once in a while, my Rena will suck in air from the intake hose causing the same type of problem. Check to make sure the tubing is secure.

The plumbers grease is silicone grease and is non toxic fwiw


----------



## keymastr (May 25, 2015)

AndreyT said:


> With canister filter, if the system is not sealed it will constantly leak water. No way around it. Does your filter leak water?
> 
> If your filter does not leak water, then the air you observe cannot possibly come from outside (unless you are feeding air into the intake tube opening somehow). If your filter does not leak water, then whatever burping you observe is just an isolated air pocket trapped in the filter after previous maintenance. It should dissipate eventually, at which point the burping will stop.
> 
> The idea that impeller pump in a typical canister filter has enough power to suck air from outside is highly questionable. Moreover, the idea that impeller pump can suck air thorough an opening _at canister level_ (where the inner water pressure is the highest) is flat out preposterous.


 
Actually, the Fluval pump is on the return side of the filter so it is pulling water through the filter, not pushing it. That is why when the gasket is leaking it pulls air into the filter, and also why I suggested unplugging the filter to see if it then leaked a trickle of water. Once you remove the vacuum by unplugging the motor then gravity will force water out of any leak.


----------

