# CO2 into canister filter intake - any problems?



## JonF

I run my CO2 air directly into the intake of my Ehiem canister filter. My thinking is this is the best way to get absorption and then circulation of the CO2 into the tank. 

I wonder though if I should be concerned that the CO2 is toxic to the biological filtration in the canister. I run about 1 bubble per 3 seconds from my CO2 bottle. 

Any thoughts would be appreciated.

Jon


----------



## pineapple

I run CO2 from pressurized systems into Eheim 2224s at the rate of 1bps with no problems at all. The CO2 does not cause damage to the biological media or cause gas locks. I am quite happy with this system since it needs nothing in the tank and does not require an in-line reactor. I have 2 items in the tank: inflow and outflow filter tubes. The heaters I use are in-line Hydor models. It seems to be a good set up.

Andrew Cribb


----------



## Botia dude

How do you feed the CO2 into the filter intake? Drill a hole in the pipe?


----------



## pineapple

Yes, a small hole in the intake pipe into which I run a small piece of acrylic or PVC pipe. Very simple.

Andrew Cribb


----------



## gpodio

Been doing the same with my Eheims for around a year now, no problems what so ever.

Giancarlo


----------



## John P.

I do this with my 2213. I have a 2.5lb CO2 bottle that seems to last forever. The CO2 is dissolved with great efficiency this way.

No probelms whatsoever.


----------



## Botia dude

Well I found a airline tubing size adapter from an old Eheim CO2 diffuser I had laying around and used a hot needle to melt a hole for it in the intake tube. It fits pretty tight and hopefully it will work fine. I just hope I won't get too much CO2 squirting out of the spray bar....

The proof will be tomorrow night before lights out. AFTER there's been a full day of CO2 being put in there at almost 2 bubbles a second.


----------



## defdac

I do it with my Fluval 404 like this:


----------



## |squee|

Aren't you guys worried that you might get the impeller damaged?


----------



## pineapple

On the Eheims I have, 2224, the impellers are made of metal. It's unlikely CO2 will damage the blades.

Andrew Cribb


----------



## TortoiseBoy

I did this for a while, but was getting a lot of gas build-up at the top of the Eheim. To be fair, I was having trouble with this at the time because I was trying to run the Eheim next to the tank rather than below (which I am doing now), but have any of you had trouble with gas build-up and then the Eheim chirping and sputtering a bit? Just curious. If you have not had this problem, I would love to go back to putting the CO2 in the intake rather than the output where it is a lot noisier.

TB


----------



## gpodio

|squee| said:


> Aren't you guys worried that you might get the impeller damaged?


I don't think that is a real possibility. There is constant water movement so the chemistry inside the canister is pretty much identical to the tank. Cavitation problems are also unlikely, not much gas really makes it's way to the return tube.

Botia Dude: I'd be cautious about sending so much gas into the filter initially. Remember this is a very efficient method so you could potentially go well over 30ppm with so much gas. I'd start around 30 bubble per minute initially and adjust things based on test results. I use 1 bubble per second in my 55 gal with this method for example. Just a precaution...

Giancarlo


----------



## gpodio

TortoiseBoy said:


> I did this for a while, but was getting a lot of gas build-up at the top of the Eheim. To be fair, I was having trouble with this at the time because I was trying to run the Eheim next to the tank rather than below (which I am doing now), but have any of you had trouble with gas build-up and then the Eheim chirping and sputtering a bit? Just curious. If you have not had this problem, I would love to go back to putting the CO2 in the intake rather than the output where it is a lot noisier.
> 
> TB


I get a build up if the filter is nearly clogged. But most filters use a bypass path or similar design to allow gas to exit the canister safely without the help of the impeller. Obviously this design relies mostly on gravity and the boyancy of the gas under water, it wouldn't surprise me if having a canister level with the tank or higher could reduce the efficiency of this design.

Giancarlo


----------



## John P.

The only time it sputters/gurgles is around 5 PM when there is a ton of O2 & CO2 in the water, plants pearling like crazy, etc. This doesn't last very long at all.


----------



## Botia dude

Well the in tank diffuser I was using is just as, if not more efficient than the Ehiem. I started off with about a bubble per second but I think I'll have to raise that to get where I want to be. I'll be testing tonight to see where things stand. So far there aren't any bubbles coming out of the canister so I think this will work for me. At least I'm crossing my fingers it will hehe. Thanks for the advice folks.

Cheers,
Anthony


----------

