# New DIY CO2 reactor not dissolving CO2 well



## trilinearmipmap (Mar 8, 2005)

I built a DIY CO2 reactor for my 75 gallon tank. Previously I had just injected CO2 into my Eheim 2028 canister filter.

I chose a reactor on the inlet side of my filter because an outlet-side CO2 reactor can slow down the filter's flow and slow the tank circulation. The reactor is about 12" long, 2" pvc.

I have no bio-balls in the reactor but I was thinking of putting some in.

Up to 2 bubbles per second, the reactor works fine. But at 2-1/2 bubbles per second, the filter outlet burps a lot of gas later in the day.

I have a few questions:

1. Will adding bio-balls really help the CO2 dissolve better? I was skeptical about this, I may try adding some, there are no bio-balls available where I live so I would have to order some.

2. How many bubbles per second would most people need for a 75 gallon tank?


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## Dusty (Apr 30, 2006)

Adding bio balls into your reactor will definitely help. Having them go through them will cause the bubbles to get even smaller helping them to diffuse into the water quicker. Plus it slows down how fast the bubbles come out the other end creating more contact time with the water.


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## diablocanine (Jul 25, 2004)

I have some 1.5" bio balls you can have for shipping. PM me if you want them....DC



trilinearmipmap said:


> I built a DIY CO2 reactor for my 75 gallon tank. Previously I had just injected CO2 into my Eheim 2028 canister filter.
> 
> I chose a reactor on the inlet side of my filter because an outlet-side CO2 reactor can slow down the filter's flow and slow the tank circulation. The reactor is about 12" long, 2" pvc.
> 
> ...


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## NE (Dec 10, 2004)

> I chose a reactor on the inlet side of my filter because an outlet-side CO2 reactor can slow down the filter's flow and slow the tank circulation. The reactor is about 12" long, 2" pvc.


I don't think this is a good idea, the flow resistance the reactor creates will be the same on both sides, also most manufacturers recommend to limit the flow on the out / pressure side to limit the wear on the pump.

Another thing that will cause you problem is that the gas will dissolve a lot faster under higher pressure which you have negative of on the inlet side but positive on the output side.

Here is another thread on the subject:
http://www.aquaticplantcentral.com/forumapc/do-it-yourself/27072-built-up-gas-diy-external-reactor.html


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## Rex Grigg (Jan 22, 2004)

You should never do anything to restrict the filter intake. You can easily damage a filter this way.

CO2 reactors should be on the output. I run ALL mine that way. And everyone I have every built is on the output.

Your reactor is actually too small for your tank. I would have gone with one at least 20" long and 2" in diameter at a minimum.

I avoid the use of anything in my reactors as even bio-balls can obstruct flow and cause problems. 

I have built around 25-30 reactors. All on the output, none with bio-balls. All work just fine. Tank sizes ranging from 12 gallons to over 200 gallons.

Also note that the flow of water in the reactor should be from top to bottom.


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## trilinearmipmap (Mar 8, 2005)

Thanks for all your advice.

DiabloCanine I would take you up on your offer of bioballs but I live in Canada so shipping would be difficult.

I have seen the plans for the DIY CO2 reactor placed on the output side of the filter. I guess I will build one. One worry I have about this is leaking of water from the CO2 input area. If the CO2 line comes off you could have a flood.

How many bubbles per second would most people use for a 75 gallon tank?


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## joetee (Apr 11, 2006)

I find that if after cleaning filter etc, there seems to get air into the reactor. This is when I get air bubbles in the tank. So I just burp the reactor of air. After this the reactor works very good. Mine is 18 inches long with a C02 rate of 50 to 60 ppm at times.


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## TexasRock (Feb 28, 2006)

Actually shipping to Canada is quite easy. You won't find bioballs for cheaper than paying just for shipping... I'd take DC up on his offer. 

Listen to what Rex and DC are saying... the reactor needs to be on the OUTPUT side of the pump/filter... it won't restrict the flow as much as you think.

Good luck with the reactor... keep us posted on what you figure out.

Keith


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## AlexTal (Mar 23, 2006)

Rex - You really don't recommend the use of bioballs inside the reactor? Do you think that they wouldn't help the CO2 dissolve into water?

Has anyone tried putting an airstone, probably one of the "limewood" or ones that produce micro bubbles, inside their reactor?


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## Rex Grigg (Jan 22, 2004)

I don't recommend the use of ANYTHING in a reactor. If you have to put something in there then the design of the reactor is wrong. Or it's too small or the water flow is too high.

And I have never had a leak where the CO2 line enters the reactor. Using the small hole method and pulling the tubing though the hole creates a gas and water tight seal.


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## aferreir (Dec 26, 2005)

Trili, beware of putting the CO2 into the canister filter... remember that the bacteria that is in the filter needs oxygen to live, and if you put CO2 into the filter this bacteria will probably die.

Regards,
Ariel


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