# CO2 question



## coool_brain (Jul 4, 2010)

hi everyone.

i have few questions regarding co2 injection

1) Does CO2 injection kill oxygen in the tank or the other way.. does oxygen injection (air pump) kill CO2 in the tank?

2) Can i inject both simultaneously into the tank or do they cancel each other and leave me with nothing?

3) How do i know that my co2 input is not too high for the fish, but good enough for the plants. 

thanks in advance


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## James0816 (Jun 19, 2009)

coool_brain said:


> 1) Does CO2 injection kill oxygen in the tank or the other way.. does oxygen injection (air pump) kill CO2 in the tank?


It doesn't "kill" it per se, however will displace it. Plants consume CO2 and release O2 during the day. Just the opposite for night time. If your tank is set up right, everything will be balanced.



coool_brain said:


> 2) Can i inject both simultaneously into the tank or do they cancel each other and leave me with nothing?


If running DIY CO2, the only time that you would want to run them simultaneously would be at night. See answer to #1. The less surface movement you have during the day, keeps the CO2 in the water longer. This of course gives the plants more opportunity to absorb it.

At night, being that plants consume O2, you want the CO2 to "gas off". By running an air stone it increases the surface movement allowing for a higher concentration of O2 in the water column.

Since you really can't shut of a DIY system, you just run the airstone at the same time. If pressurized, you have soleniod on a timer and it will shut the CO2 automatically.



coool_brain said:


> 3) How do i know that my co2 input is not too high for the fish, but good enough for the plants.


Invest in a drop checker. This will tell you how the concentration is.
BLUE = Too Low
GREEN = Just right
YELLOW = Too Much


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## coool_brain (Jul 4, 2010)

thanks james

but this drop cheker... it functions based on 'pH' or 'CO2 concentration'?
as fas as I know, high acidity(low pH) doesn't always mean high concentration of CO2. right?


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## James0816 (Jun 19, 2009)

coool_brain said:


> thanks james
> 
> but this drop cheker... it functions based on 'pH' or 'CO2 concentration'?
> as fas as I know, high acidity(low pH) doesn't always mean high concentration of CO2. right?


It goes by saturation of CO2.


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## WhiteGloveAquatics (Sep 3, 2009)

You CAN shut DIY off at night however you need atleast a accumulator twice the size of your brewing bottle.

I do this with great success, but once i crack the valve in the morning I have to throttle out the gas build up so it doesnt OD the tank.

Id just run a stone in conjunction at night and forget about it, its much easier and less messy(once you get the hang of it its clean but Ive had a few bottles blow at night, granted they are in a sealed plastic tote for such situations it still sucks to clean)

james is right, a drop checker is a planted tanks best friend. You do need to read the directions though as the indicator solution needs to be changed twice I month I think I may be wrong.


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## jrman83 (Jul 9, 2010)

When you guys refer to night and your CO2 shutting off, is that timed with your light period or we talking real day/night?


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## Alabastercities (Sep 26, 2010)

The CO2 should be synchronized with your tank lights. The photosynthesis taking place in the tank requires both light and CO2, so if the lights are turned off the CO2 is not being used by the plants. An excess of CO2 may be harmful to any fish in your aquarium.


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## James0816 (Jun 19, 2009)

jrman83 said:


> When you guys refer to night and your CO2 shutting off, is that timed with your light period or we talking real day/night?


If you're running a pressurized system using a solenoid and timer, ideally you want to set the CO2 flow to begin roughly one hour before the lights come on. This allows the level to build up slightly. Then at night (or when you turn off the lights) you want to have the air stone come on one hour after the lights go off.


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