# CO2 injection into Canister Intake?



## evercl92 (Aug 14, 2006)

What are the general thoughts/ideas on this? 
I currently have the CO2 injected into a limewood airstone and then into the intake of a powerhead (and then sent across the tank). I get pretty good diffusion, but I'm thinking I could get alot better if it were connected to the canister somehow. I'm sure connecting to the output of the canister is probably best.

My concern would be that the CO2 bubbles might cause airlock / stress on the impeller of the canister. But would it be that much of an issue if the bubbles were already really small, do to the limewood airstone?

Tank specs:
120gal, Eheim 2028, CO2 @ 4-5 bps

My current setup looks like:


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## goalcreas (Nov 20, 2006)

I like the idea.
I plan to do this on the 75 gallon that I will be setting up the end of this month.
I think that the eheims have been said to be able to do this with not any problems, but am not sure.
I think that the Rena's have been said to have some trouble with this, but again, not too sure.
I actually am thinking about doing it on a Fluval, so we will see.

I might add that I will be running the co2 line over the tank wall and plugging it right into the ADA lily pipe intake.


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## redstrat (Apr 3, 2006)

Why not just use a reactor if you have a canister filter? you may be able to cut that bubble rate down some.


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## goalcreas (Nov 20, 2006)

Reactors are a great idea, if you have the flow.
If you have limited flow and don't want to upgrade or add a 2nd canister, then it can become an issue.


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## redstrat (Apr 3, 2006)

what canister are you running that this would be an issue, small or less flow restrictive reactors can be built. I would imagine a canister with enough capacity for a 120g tank could drive a reasonable reactor.


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## goalcreas (Nov 20, 2006)

I did not say it was a problem, for him or me, just stating that that might be a reason not to.


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## redstrat (Apr 3, 2006)

Gotcha, I was just wondering because it seems many canisters even the small ones would be more than enough to drive a reactor without to much trouble. another reason to avoid a reactor I guess would be if your going for CO2 mist instead of 100% dissolution, some prefer this method. Personally I feel I get the same results with less CO2 using a reactor and I'd rather have less bubbles floating around so its perfect for me, but not everybody.


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## goalcreas (Nov 20, 2006)

And for smaller tanks with smaller filters, I am sure you are correct about making smaller reactors.
I am actually thinking about going PPS and running 24/7 anyhow, but because I want to try the method of running thru the lily pipe, I am scratching the reactor idea, at least for now.


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## redstrat (Apr 3, 2006)

goalcreas said:


> And for smaller tanks with smaller filters, I am sure you are correct about making smaller reactors.
> I am actually thinking about going PPS and running 24/7 anyhow, but because I want to try the method of running thru the lily pipe, I am scratching the reactor idea, at least for now.


sounds great, reactors aren't the best choice for everyone or every situation.


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## evercl92 (Aug 14, 2006)

I thought about the reactor idea. I do have an extra gravel tube, and some bio balls. I don't know if I want the challenge of hooking it into my system....


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## DonaldmBoyer (Aug 18, 2005)

That's how I've done my CO2 for a few years now.....through the intake of Magnum 350 canister filters. I have had no problems with bubbles, large or micro. The trick is to adust the flow rate on the quick connects to about 2/3's "open" and place a micro polisher filter in there. I would say I have close to 100% dissolve rate for my CO2 gas. It works wonders, and I haven't had to fuss with a reactor. For now, this I have found this to be the best way.


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## furballi (Feb 2, 2007)

If there is excessive noise from the filter, then you're injecting too much CO2 for the given mass flow rate of water. It's not that hard to raise the CO2 level in the tank to 20 ppm.


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## abnormalsanon (Jun 6, 2006)

I use this method on both of my tanks (Eheim 2213s) and it works just fine.


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## houseofcards (Feb 16, 2005)

I injected co2 into the intake of my Eheim Ecco for quite sometime without a problem. I actually cut the strainer and fit a micro airstone inside the cut section so you didn't even see the airstone and the bubbles where already reduced in size by the time it got to me filter. I personally prefer the ceramic diffusor method. One question, why don't you just hook up a spraybar horizontally on your outlet and let that blow the co2 bubbles across your tank via the airstone or a small ceramic diffusor. You probably wouldn't need to powerhead in the tank if you do that.


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## Muirner (Jan 9, 2007)

I currently have a 2' reactor (1" Schedule 40 PVC) and i'm injecting on the intake side of my XP3. Even with the flow rate turned down, i still notice air building up in the top of my filter. I'm not sure if it's CO2 or air, i'll have to try to get a gas meter down to check that.

If it were me, and I were to do it again (which i will) I'll be building a 2' 1.5" reactor, to inject on my output line. Make sure you set it up so flow into the reactor goes from top to bottom, this will allow for maximum exposure time for the bubbles.

My reactor looks like this







(i'm looking to sell this one) It was simple and easy to make, fairly cheep too.


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## evercl92 (Aug 14, 2006)

houseofcards said:


> I actually cut the strainer and fit a micro airstone inside the cut section so you didn't even see the airstone and the bubbles where already reduced in size by the time it got to me filter. One question, why don't you just hook up a spraybar horizontally on your outlet and let that blow the co2 bubbles across your tank via the airstone or a small ceramic diffusor. You probably wouldn't need to powerhead in the tank if you do that.


There's already a spraybar on the output of the canister, another reason I was thinking this would be a good idea. I'd rather not cut the prefilter on the intake. What I may do though, is squiggle CO2 line between the prefilter bars, then attach the airstone inside the intake tube itself.


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## furballi (Feb 2, 2007)

Muirner said:


> I currently have a 2' reactor (1" Schedule 40 PVC) and i'm injecting on the intake side of my XP3. Even with the flow rate turned down, i still notice air building up in the top of my filter. I'm not sure if it's CO2 or air, i'll have to try to get a gas meter down to check that.
> 
> If it were me, and I were to do it again (which i will) I'll be building a 2' 1.5" reactor, to inject on my output line. Make sure you set it up so flow into the reactor goes from top to bottom, this will allow for maximum exposure time for the bubbles.
> 
> ...


Don't have an XP3 so I cannot provide a viable mod package to the pump.

Since you're going to build a new reactor, I would recommend an inverted 2' long U-tube reactor positioned at the intake side of the filter. Position the water intake and exhaust barbs at the ends of this verticallly positioned U-tube reactor. Introduce CO2 near the bottom of the intake side of this U-tube. The CO2 gas will rise to the top, along with the incoming tank water. Any un-dissolved CO2 gas will accumulate at the top of this U-tube, allowing additional time for the gas to mix with the water. If you have very high water flow, then you can increase the surface area for gas exchange in the reactor by increasing the length of the inverted U-tube in the horizontal direction (2' long by 1' wide). Note that the U-tube will result in additional "head loss" at the pump.


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## evercl92 (Aug 14, 2006)

Today will be day 1.5... as I got the switchover done partway through yesterday. I turned it down to about 1.5 bps, and still got pretty good pearling by the end of the day. Plus, I don't have the 'haze' of almost dissolved CO2 coming from the powerhead, so the tank actually looks clearer.


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