# co2 question



## JAXON777 (Jan 4, 2007)

I have a question regarding co2. My tank is 5ft long and it was suggested that I use two sources for my co2. Should I get two smaller canisters and build reactors for each with the outflow coming from both sides of the tank or should I get 1 big canister and say a powerhead to distribute the co2 throught the tank.

Thanks for the help

Jaxon


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## orlando (Feb 14, 2007)

2 canisters with two reactors and a regulator with a two tank manifold.


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## JAXON777 (Jan 4, 2007)

What size co2 tank is recommended. Do they get taller the bigger or just wider around?


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## evercl92 (Aug 14, 2006)

JAXON777 said:


> What size co2 tank is recommended. Do they get taller the bigger or just wider around?


I personally have a 20lb tank for my 4x2x2 tank. I expect it to last about 18months.

As tank size increases, they get a little wider, but mainly taller.


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## JAXON777 (Jan 4, 2007)

How tall is the 20 lber


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## Mr. Fish (Oct 24, 2007)

Just use a Reactor.....


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## exterminator (Mar 26, 2005)

My 20lb tank is 27.5" with the handle on top of it. It doesn't fit into my under-aquarium cabinet.


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## evercl92 (Aug 14, 2006)

exterminator said:


> My 20lb tank is 27.5" with the handle on top of it. It doesn't fit into my under-aquarium cabinet.


I could measure to be exact, but that sounds about right.


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## gotcheaprice (Sep 4, 2007)

orlando said:


> 2 canisters with two reactors and a regulator with a two tank manifold.


 Why 2 canisters?
1 canister, 1 regulator, a 2 port manifold, 2 needle valves, 2 reactors I would think would be best.
1 in your filter outake(assuming you have a canisters) and another in your circulation, ie. powerhead.


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## orlando (Feb 14, 2007)

For a 5 foot tank I use two canisters and one regulator with manifold for two bubble counters. Then two in line reactors on the outflows.


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## Amazon_Replica (Nov 24, 2007)

geez, 

I am switching over form diy to pressurized as soon as I can find a tank. I was told to look for a 2.5 - 5lb tank at the most, should last over a year. I have a 125gal 72" x 18" x 24" so you think I should go to a 20lb+?


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## evercl92 (Aug 14, 2006)

Amazon_Replica said:


> I was told to look for a 2.5 - 5lb tank at the most, should last over a year. I have a 125gal 72" x 18" x 24" so you think I should go to a 20lb+?


I run about 1-2 bps on my tank, to get adequate CO2 levels in my 120g. I don't see it feasible for a 5lb tank to last you a year, unless you're gonna run 1b/5sec.


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## gotcheaprice (Sep 4, 2007)

Amazon_Replica said:


> geez,
> 
> I am switching over form diy to pressurized as soon as I can find a tank. I was told to look for a 2.5 - 5lb tank at the most, should last over a year. I have a 125gal 72" x 18" x 24" so you think I should go to a 20lb+?


Yep, I'd go with a 20 lber. I'm gonna us eone for my 55 and 10 gallon.

Also, orlando, do you mean 2 co2 canisters, or 2 canister filters?
I'm sorta confused on why you would really need 2 co2 canisters, and how one regulator would work with 2 canisters.


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## orlando (Feb 14, 2007)

2 canister filters...


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## Rex Grigg (Jan 22, 2004)

Unless you get a honking big canister filter you will have flow problems. And generally one honking big canister filter costs more than too big canister filters.

And don't forget redundancy.


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## orlando (Feb 14, 2007)

Rex Grigg said:


> Unless you get a honking big canister filter you will have flow problems. And generally one honking big canister filter costs more than too big canister filters.
> 
> And don't forget redundancy.


Agreed, as said before two filters is better than one. If one fails you will have trusty #2 there.


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## Dany (Oct 28, 2006)

Rex Grigg said:


> .........And don't forget redundancy.





orlando said:


> ........ Yes, don't forget redundancy.


Sorry to go off topic but does anyone else see the irony in this ?


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## orlando (Feb 14, 2007)

I had to do it... I did...


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## BryceM (Nov 6, 2005)

hehe.

To be even more redundant..... Having two canister filters is a good idea regardless of what you do with CO2. It's nice to be able to clean one thoroughly and not worry about what effect it has on the biology of the aquarium.

20# cylinders are carried by almost all gas suppliers. 10# cylinders exist too, and would be a good compromise if you could reliably find them. For comparison, my 20# tank lasts about 7 months on a 180g aquarium but I dose it pretty heavily. It goes through an in-line reactor for 11/hrs day with only a little surface aggitation.

As I see it, there are a few good options for distributing CO2 into large tanks. If you have good circulation it probably isn't necessary to go with 2 separate inputs. Trying to meter CO2 into two places is twice as much work. I'd use a single reactor on one of the canister return lines. I'd place both canister intakes on one side of the aquarium and both returns on the other side. If the tank is to be heavily planted I'd probably also supplement things with a powerhead or two.

The thing that you need to avoid is a zone that doesn't mix much with the CO2 enriched water. If you dump all the CO2 into one end of the aquarium and don't provide a mechanism for mixing water to the entire tank you might see issues. If you use enough flow, a single point of CO2 input shouldn't be a problem. Personally, I use a return spraybar that is the length of the 6' aquarium which provides an almost even flow of CO2 throughout the tank. It seems to work well but it's probably overkill.


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