# Overflow and co2



## A_Shea (Jun 2, 2007)

Hello all! So i have a 58 gallon Oceanic with a built in overflow in which i would like to set up as a planted tank. However i have heard and read very contradicting arguements about co2 being used in tanks with an overflow. Does the aeration from the water flowing to the sump cause the co2 to be released from the water? Or is it a minimal amount that shouldnt be worried about? I just dont want to pump in a ton of co2 into the aquarium for it just to be wasted and my tank fail. I would be using pressurized co2. Also if its not a problem where would be the best place for the diffuser or injection of co2 into the system? 

Any help would be greatly appreciated!


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## James0816 (Oct 9, 2008)

I would fathom a guess....granted this is just a guess here.

That if you have good diffusion in the tank, I would think the gas loss would be minimal. Don't quote me on that though.

You could use an inline reactor on the return line from the sump.


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## darkoon (Jun 7, 2010)

overflow will increase surface agitation, and it will degas co2 much faster. it is suggested to have some ripples but not to break the surface.


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## deicide (Sep 1, 2009)

Overflow will affect Co2 now matter how to look at it. The question you should be asking is whats the better method of adding Co2 in a tank that has an overflow. 

To answer that--misting the Co2.


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## Bert H (Mar 2, 2004)

...or just increase the bubble rate to make up for the degassing.


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## A_Shea (Jun 2, 2007)

Those are some very good thoughts. Thank you for your input. What exactly is misting the co2??? 
The reactor on the return line sounds like a very good idea as well.


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## darkoon (Jun 7, 2010)

this is misting
http://www.aquaticplantcentral.com/forumapc/diy-aquarium-projects/44053-tiny-super-efficient-co2-reactor.html


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## deicide (Sep 1, 2009)

A_Shea said:


> The reactor on the return line sounds like a very good idea as well.


An overflow based setup is not like a closed, so trying to use a reactor (though possible) is highly inefficient (loads of Co2 needed which results is burping)! Misting will give more consistent Co2 levels through out the tank and you'll be able to fine tune the output because you'll see where the Co2 is going. I know this because I did this on a 90gal for 2 years and tried all types of methods (reactor, mazzei, misting via pump, etc) to maintain good levels and keep plants healthy, so I have actual experience on this topic.

I've since downgraded and after a long hiatus I'm slowly making a come back. Here's a simple but effective misting setup which you can see I'm getting descent growth using a HOB filter--nothing fancy.










Old setup:


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## newguy (Mar 18, 2006)

researching overflow while stumbled on this old thread, sorry to bump but to clarify there is no co2 diffuser more efficient than inline diffuser, with waterflow and co2 bubble going opposite direction, it is a 100% co2 absorption. Versus misting and what not where tons of co2 bubbles escape to the surface and are wasted, not to mention it disturbs the tranquil stillness of the water. Ceramic plate quality also plays a big role. One should always go with inline co2 diffusion if possible unless you like seeing tons of tiny bubbles in your tank...

Now back to the overflow, i am surprised not a single person here has actually done it. Tons of response from various threads of *maybe* *dont quote me* etc..but noone has a 50 gallon+ overflow planted tank? I would imagine there is very little surface movement/gas exchange once you have the overflow established. There is no surface movement in the sump and there is no surface movement in the tank, isnt it just like a regular canister then?


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## WhiteDevil (May 7, 2009)

I have a 210g planted Reef Ready tank equipped with a aquapro 400 wet/dry system running compressed Co2, I go thru 5 pounds of Co2 in 8-10 weeks now, Ph maintained at a constant 6.4Ph Gas off is minimal if any, I maintain a constant 28ppm in the tank of Co2(dissolved).

I run my Co2 thru my eheim pro3 2080 on the same tank via a reactor. I have NO issues.
cruddy pic but here is the filter system and Co2 system









here is the tank its on









as you can visually see, I have NO ISSUES running a sump on a planted tank. I do have surface agitation via returns.


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## JukeFish (Mar 15, 2011)

newguy said:


> Now back to the overflow, i am surprised not a single person here has actually done it. Tons of response from various threads of *maybe* *dont quote me* etc..but noone has a 50 gallon+ overflow planted tank? I would imagine there is very little surface movement/gas exchange once you have the overflow established. There is no surface movement in the sump and there is no surface movement in the tank, isnt it just like a regular canister then?


I use an internal overflow in my 90g but not a sump. Rather, I have the intakes of my two XP3s sitting in the central overflow. I try to keep the water level in the overflow just a little below the tank level; maybe within an inch or so. It's quieter that way. I return the water to the main tank via spray bars on either side of the overflow. I also keep my heaters and diffusor in the overflow. I've had my share of challenges but I can keep the CO2 level where it needs to be.


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## jschall (Apr 13, 2009)

I don't think an overflow would HAVE to disturb CO2 to the point where it'd be a problem. If you have a good standpipe, no surface disruption in sump, lid on sump, etc. I don't think it'd be an issue.


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## WhiteDevil (May 7, 2009)

Thats the trick JSC, Lids. However if it can be injected elsewhere the amount lost will be even more minimal then going thru the sump. I run mine thru an eheim pro3 and maintain those levels I posted just fine, even more so since I covered the tank and sump. I think people just think aggitation=gas off and while it does gas off it doesnt gas off enough to disrupt the ppm in the water column itself, once that electrode senses a Ph raise it injects Co2 back into the tank for a minute or two and shuts off again.

A HOB would cause more issues then a sump will.


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## apistomaster (May 24, 2008)

Seems to me if you are using a wet/dry filter your CO2 consumption would have to be increased.
At least if you have a drip plate over high surface area to volume media such as this and note the tight lid.


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