# Canister Filters and Air Stones



## burncycle95 (May 8, 2009)

I am setting up my tank again which has been in disuse for quite a while. In the past I had a HOB filter and didn't use an air pump or stone. I figured that the spill way of the HOB filter created enough surface disruption that I didn't need an air pump and it worked fine this way for over a year. Now I have purchased a canister filter which obviously creates no surface disruption. Do canister filters have any air space inside that allows oxygen to enter the water or should I add an air pump and air stone now? (there are no fish in the tank yet)

My tank is a 37 gallon and the canister filter is a Fluval 405.

Thanks!


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## RyanR (Apr 29, 2008)

As long as there's sufficient surface agitation, you're OK. Can you have the canister return shoot across the surface? Barring that, my personal preference would be to add a power head. That'll add some agitation, and you can inject some bubbles if you want/need using its venturi.

I don't like air stones. The pumps are noisy, and the bubbles are ugly. 

-Ryan


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## prov356 (Sep 20, 2006)

I just direct the outflow of the canister toward the surface to get some agitation. Some canisters come 
with a spray bar used to provide surface agitation. A small water pump will work as well, so you can 
avoid the air bubbles in the tank if you don't like how that looks.

But, to answer your question, the water at the surface of the tank is where any and all gas exchange 
will happen, not anywhere in the canister filter. I find that with no surface agitation, a film can develop 
over the surface and hinder the gas exchange.


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## burncycle95 (May 8, 2009)

Ah ok great, so just directing the exhaust from the filter toward the top is enough? Does it just need to create a "hump" in the surface water or does it need to actually break the surface a bit with water pressure? I too, don't like the look for bubbles if I can avoid it.

Thanks!


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## prov356 (Sep 20, 2006)

Just so it causes a 'ripple' over the surface. It doesn't have to break the surface completely. If it did, 
you'd end up with bubbles from doing that. Just get a ripple going across the surface.


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## burncycle95 (May 8, 2009)

Prov, you have a been a great help, thank you very much. I have one more question, do I need to get anything extra for my Fluval 405 or does it come with everything I need? I see people talking about adding "floss" and lavarock for bbq's etc in certain trays as well as ceramic rings etc. Should I got get some of these things or does the filter come with everything I need? Is there a good resource I can go to and read about the specifics of how canister filters work, how to clean them etc?


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## prov356 (Sep 20, 2006)

> Should I got get some of these things or does the filter come with everything I need?


It should come with everything you need, but I've not purchased that canister, so can't say for sure. I 
usually just Google the canister like 'Fluval 405' and you should find a wealth of info and even sites 
with spare parts, etc.

I found this site. It does come with media, so I'd go with that. I'm ready to run for the day, so if you have 
more questions, post back.

HTH


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## boredatwork (Sep 14, 2007)

You can also get a surface skimmer for you canister. For larger tanks I think they are priceless. A 37g may be OK without it if you oversize the filter. But they are especially handy/necessary if the water surface starts to develop any buildup. From what I have read they work a lot better than spray bars at cleaning up the water surface.

When I started using a surface skimmer on my 125g the water surface was beyond disgusting and it cleared it up in only a few minutes and keeps it quite literally crystal clear.


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