# Canister Pulling In Air



## Justin1982 (May 28, 2008)

I have a 75 gallon tank with decent filtration (2 Emp 400s a power head with filter & a Fluval 404) But I am a little concerned about one thing. I have a air line attached to this fairly large power head in order to increase oxygen in the tank, the problem is that the Fluval 404 sucks up a lot of air and every 25 minutes or so I can hear it purge trapped air back into the tank. There is always air trapped in it. Even after it burps out trapped air I will kneel down and give it a little shake and a whole lot more trapped air comes out. This has become somewhat frustrating considering I have to do this at least 5-6 times a day. I remove the canister every other week to clean off the foam so I know it is clean. Is the air that comes out toxic though, after being trapped inside the canister for a half an hour to an hour and a half? I have tried moving the canisterâ€™s intake line all over the tank and it still sucks up air. :?


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## Ispintechno (Mar 27, 2008)

Thats a pile of filtration for a 75G tank 

The worst part of it I would think is it might be hard on your impeller assembly as it sort of "runs dry" 6 times a day. Might increase wear and tear. The air in the filter it self might actually be beneficial for your bacteria colony actually, as it gets purged out in a timely fasion before becoming stale.

I'd say remove the air line unless you like the look of the bubbles, 2 emperor 400's + the fluval covers your gas exchange nicely. Water O2 saturation maxes out, I bet the air coming from the powerhead has a minimal effect. No bubbles blowing into the fluval from the powerhead, no more air in the fluval causing wear and tear.


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## F8LBITEva (Nov 9, 2007)

I have the exact same problem with my Fluval 404, I thought it was because I have a surface skimmer attached to my intake but now it sounds like it might be a Fluval problem. Ill stay tuned for any ideas from our other forum members.


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## Heyguy74 (Aug 11, 2005)

Just remove the airline from the powerhead. You are not adding oxygen to the water. With all the filteration you have and the great water movement there is no need for the airline. The emporers should provide plenty of surface agitaion by themselves. If the problem continues after removing the airline, you may need new orings for the cannister. Make sure all teh connections are tight and are sealed properly.


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## Justin1982 (May 28, 2008)

Thanks for the Advice. I had the powerhead setup so it would shoot out tiny bubbles not big ones. But I removed the airline from the powerhead. Although I really dont see any oxygen in the water without it. The lip on both EMP400s in under water by almost an inch, so the water just kind of falls back into the tank without really breaking the surface of the water. Besides that there is plenty of turbulance in the water. Not to much. I just wanted to make sure there was enough oxygen in the tank is what I was trying to do.



Ispintechno said:


> Thats a pile of filtration for a 75G tank
> 
> The worst part of it I would think is it might be hard on your impeller assembly as it sort of "runs dry" 6 times a day. Might increase wear and tear. The air in the filter it self might actually be beneficial for your bacteria colony actually, as it gets purged out in a timely fasion before becoming stale.
> 
> I'd say remove the air line unless you like the look of the bubbles, 2 emperor 400's + the fluval covers your gas exchange nicely. Water O2 saturation maxes out, I bet the air coming from the powerhead has a minimal effect. No bubbles blowing into the fluval from the powerhead, no more air in the fluval causing wear and tear.


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## Ispintechno (Mar 27, 2008)

O2 saturation isn't really a visable to eye thing, the bubbles you see floating through the water isn't necessarly an indicator of O2 levels, it's the surface agitation that releases Co2 and adds oxygen. Whether its bubbles from your powerhead or an airstone releasing bubbles traveling through your tank, it's only at the surface where the bubbles pop or where the surface is disturbed where any gas exchange takes place at all. Maximize the surface disturbance, and not have dead spots of stagnant water below (which with your gear hooked up there is no way), you have reached maximum O2 saturation.

Your fish with your set-up have all the O2 they need I'm very sure, don't go by bubbles made directly from the filters, actually too many bubbles I understand can make new problems for fish resperatory.

Also, I use a Fluval 304 canister, once a year or so I use vasolene (sp?) on the outer rubber ring sealing the top portion of the canister to the plastic cantainer, I hope it keeps the ring from cracking and leaking/alowing air to enter. So far so good for many years.


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## Ispintechno (Mar 27, 2008)

Also, if you want to really increase the maximum allowance for oxygen in your water, lower the temperature gradually. Water of 78 degrees holds more oxygen than water heated to 80 degrees and so on. The molecules move farther apart at higher temperatures not being able to hold the oxygen in as well... basically grade 9 science with a practical application


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