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controlling co2 levels with yeast system


New Member
16 Jun 2008
is there anyway the rate of co2 entering the tank can be altered with a yeast based system? such as using a clamp on the co2 tubing etc?


21 Feb 2008
trc007 said:
is there anyway the rate of co2 entering the tank can be altered with a yeast based system? such as using a clamp on the co2 tubing etc?
Would not recommend, too much pressure and the bottle or the tubbing might not hold it, when I run a yeast based system I run two bottles and changed one on Wednesday and the other on Sundays (these were the nutrafin bottles with DIY solution), then run an air stone during lights out so that I wouldn't poison the fish. Just turn the airstone off 3 hours before the tank lights come on and start it at the same time lights go off, plants won't use CO2 during lights out.


29 Jan 2008
You can't regulate the CO2 produced by yeast with any kind of clamp/valve/screw - you'd just cause an extremely sticky explosion.

Once the yeast in your reactor is producing CO2 there are only two practical ways you can regulate it:

Temperature: All life processes (including yeast's production of CO2) get faster as the temperature increases (within the tolerable range for that organism). Most processes double with an increase of 10 degrees C.

Some people (including me) utilise the heat generated during the day by the light's starter units to increase production during the day, and let it tail off a bit at night (ie, I just stand the CO2 bottle on the starter unit - low tech!)

Other people (especially in cold parts of the world) keep their yeast generating unit (the bottle, etc) in a bucket or tank of water containing an aquarium heater - they can then regulate the production of CO2 by changing the temperature the heater is set to.

Apart from temperature, you can regulate the amount of CO2 dissolving in the water by changing the efficiency of your diffusion methods. To reduce CO2 levels you could raise a glass diffuser higher in the tank, place it in an area of minimal flow, or with Hagen's diffusion ladder you can insert the CO2 tube higher up the ladder (there are three places to put it.

I suspect from the fact that you're asking about clamps you're looking to reduce the amount of CO2 in the tank water, so in your case raising the temperature of the reaction chamber isn't going to help, and you'll have to look at reducing the efficiency of the diffusion method.

Are you sure you want less CO2? is it causing the animals a problem? If not, I'd just let keep going as it is.

With more information on what you want to do people might be able to give you better help.



Edit: As London Dragon says above, you could also run an airstone at night if you want to reduce the levels of CO2 in the tank at night. I was just looking at ways to regulate the CO2 going into the tank, but if lower night levels of CO2 are what you're after then London Dragon's suggestion is the easiest one to automate.


16 Mar 2008
Dalkeith, Scotland
get an airline tubing T-joint so that there is spare bit of tubbing running off to air and not to tank

clamp that bit of tubing when lights are on so c02 goes to tank

take clamp off when lights are off so co2 goes into room instead (it will mostly take shortest path of escape)

downsides - manual method, you have to be there for lights on, need to make sure escape tube is high above source

upside - no co2 in tank when you don't need it

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