making DIY CO2 last longer

>From: duncand at sprynet_com
>Date: Mon, 20 May 1996 21:13:51 -0700
>Subject: DIY C02 recipie doesn't last
>This is for all the DIY C02 users out there.
>I'm running one bottle on a 75g and one on a 50g. The recipie I got from a FAQ 
>file off of the AquaLink web site calls for 3 cups sugar and two tablespoons 
>yeast (roughly 1 packet) to the two litre bottle. The file states that this is 
>supposed to last about two weeks. I'm barely getting one week on mine.
>Can anyone give me their recipies, tips on stretching out the time between 
>refills, etc..

Try putting a little baking soda (sodium bicarbonate) into the mix, about
half a level teaspoon. As yeast digests the sugar and releases CO2, it also
makes the sugar solution acid. The baking soda will buffer the solution so
it does'nt become too acid. 

While you can vary the rate and length of CO2 production by adjusting the
amount of sugar, yeast, temperature, etc., IMHO the addition of baking soda
will make the biggest difference. Of course, you will have to experiment
with the amount of baking soda that works best for you.

Where I live, the ambient temperature varies from 26 - 30 degrees celcius.
My 300 ml (small coke bottle) CO2 generator lasts only a week without baking
soda. I use half a cup of sugar and a pinch of yeast. After I added a little
baking soda, I could make the CO2 generator last 3 weeks with no problem.

Hope this helps!

kevinlim at pacific_net.sg