# Does Running An Airstone Reduce Co2?



## pbohart (Jan 9, 2005)

I know the purpose is to add O2 to the water in cases where CO2 is too high. But my question is - does running the airstone reduce the CO2 ppm in your water?

Also - is there anything else that I am missing about airstone use?


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## Widefx (Oct 31, 2006)

Yes the adding of any air into the system will reduce the amount of C02 in the water.


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## spypet (Sep 15, 2006)

O2 may help reduce certain algae, and your fish need it to live.
what reduces Co2 is not the O2 itself, rather how much the
surface water tension is broken by water flow and bubbles popping.

that's why I use a Hydor Ario (with or without LED light) for O2.
it's as cheap as an air pump, tubing, and airstone. it's completely quiet,
and produces fine tiny air bubbles that no airstone could ever achieve.

My Hydor Ario also doubles as my Co2 diffuser since the impeller does
such a fine job chopping up my bubbles into a very fine mist of Co2
that floats horizontally across my tank water.

I prefer mounting it low on your side glass, not the bottom.
the white tube is my Co2, and the black tube is my O2.
both get chopped up by the impeller and released as uber fine mist
that you barely see in this photo as white dots center left and up,
which are finer than some of the best Co2 diffusers I've ever seen.


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## Lycosa (Oct 16, 2006)

Popular misconception. CO2 will not lower oxygen concentration and oxygen will not lower CO2. As Spypet said, CO2 will easily offgass back into the atmosphere as the surface tension of the water is broken (kind of like opening a soda...its the running theory of why mentos + diet coke = large fountain). Running an airstone does exactly that, breaks the surface tension of the water so that more surface area of water is exposed to air. Another misconception is that the airstone itself is the primary source for oxygen in an aquarium. In fact, it is the air bubbles moving the water to the surface so that it can come in contact with the surrounding air that is the primary means of introducing the oxygen into the tank. 

More turbulence in the water = Less CO2 Concentration = More O2 Concentration.


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## DrewWoodside (Apr 1, 2008)

For the list of fish and tank in my signature do I need to run an airstone? If I run an airstone all the time am I completely losing any C02 I put into the tank? Does a well planted tank produce enough oxygen to take the place of an airstone? I've heard that it might be best to run an airstone only at night can anyone confirm this? I find this a tricky subject cause I want my plants to grow but I can't tell if my fish are being oxygen deprived. Thanks for any help!


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## lauraleellbp (Feb 3, 2008)

Your fish will tell you if they're O2 deprived; they'll be at the surface of the water all the time where the O2 concentration is higher. If they're swimming around the tank normally then you're OK.

I'd personally recommend running an airstone at night when the CO2 is off; this is when plants actually reverse their process and absorb O2 and release CO2, so this is the time that O2 levels in the tank most often become critical for the fish.


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## BSS (Sep 24, 2004)

I was having the O2 deprivation issue most often after water changes. Since adding an airstone during the lights off period, no more fish gasping. Personally, I didn't find that it lowered by CO2 levels by that much. Sure, theoretically, it has to reduce it some. But, it was a very small level from my observations (though no hard measurements to back any of this up ).


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