Tuesday, March 29, 2011


I decided to use DIY CO2 for this setup to speed up my plants growth. Both non CO2 and daily Excel dosing does not give enough grow rate.

My DIY CO2 setup is pretty simple:
- 2 bottles of 1.5L soft drink (empty)
- 2 bubble counter
- 2 check valve
- Airstone
- CO2 hose

I did not use diffuser since it may not generate enough pressure to push CO2 through but I put airstone under filter inlets. That way most of the CO2 will be suck in by filter but it may cause airlock in some filter if lots of CO2 is created. Buble counter function as an indicator which bottle need to change. The check valve is to prevent CO2 from leaking out when one of the bottle being replace. I did not premix the solution together at the same time.

Simple sketch

I've been researching through out the net about DIY CO2 recipe and found that wine yeast suppose to be used instead of normal bread yeast. Apparently alcohol is toxic to yeast and alcohol is by product when yeast consume Glucose to generate energy in Anaerobic condition. Wine yeast on the other hand can tolerate highest level of alcohol and acidity. Thus in theory wine yeast will give you longer CO2 generator

Aerobic condition:

Glucose + O2 --> CO2 + H2O + Energy

Anaerobic condition:

Glucose --> CO2 + Alcohol + Energy

Searching around for wine yeast and found out that it cost 10 times more than normal yeast from supermarket. So forget about the idea of using wine yeast and use instant yeast instead (Saccharomyces Cerevisiae) from Bake King

My recipe:
- 2 cup of sugar
- 1/4 teaspoon of yeast
- 1/2 teaspoon of baking soda
- 1000 ml of water

Honestly it really not bad. I was haunted by post on forums, people was saying that DIY CO2 have unstable output. On contrary, I was able to get good stable output at least 0.5 bps for a month.

Update (12 October 2011)
BPS output from 1 bottle through out 37 days.


  1. Why for do you add the baking soda? On your first sketch there is no soda mentioned, but the latest recipe had it. Does it help to stabilize the solution?

    Also I think the very important point here is usage of 2 bottles instead of one (as many people do) because in this case you have more stable CO2 output (if you start your bottles with some delay, say a week).

  2. I was told, it will stabilize the pH, so that the yeast not die easily.

  3. this co2 mixture lasted a month ?

  4. depend on how you look at it. I update above article with picture of CO2 BPS generated from 1 bottle for duration of 37 days. With this info I hope you are able to determine when the best time to change the solution to keep the BPS.

  5. I heard the solution stinks !
    Is it true ?
    I think you also need a valve to shut off the CO2 supply during the night. Correct ?

    1. It does stink but not that bad, sweet smell kind stink.

      You can add splitter, one to the tank and one to the valve. During at night you open the valve which will release all the CO2 to the air. Do not add valve on hose that going to the tank because you might end up with messy stinky liquid all over due to exploded bottle.

  6. Does the bottle for CO2 must have a same heigt with the tank, i mean height of bottle cap = height of tank surface. Because i've Made it, the bottle is under the tank, and its cant to get in water tank. What should i do?

    1. to be honest, I have no idea. I never put it under tank. However it could matter since the pressure generated by DIY CO2 is pretty low.

      By the way, how do you introduce the CO2 to the tank? because CO2 diffuser not gonna work, not enough pressure. You can use air stone instead.