Ammonium, Yeast DIY

Greg wrote:

>Help. Where does ammonium come from? I thought ammonia was what the 
>fish secrete. If so, something must first turn ammonia into ammonium ... 
>Where does that something come from? TIA.

Fish do secrete ammonia which is NH3.  In the presence of an acid 
environment, it gets converted into the ammonium ion, which is NH4+.  

Douglas wrote:

>Can anyone give me their recipies, tips on stretching out the time between 
>refills, etc.. My wife says to add more sugar to the bottle. I also thought
>placing the bottle on a heating pad might increase c02 output, but then
>that might just make it burn up faster.

Cut back on the amount of yeast, use about 1/2 a teaspoon, and try adding 1-2 
tablespoons of baking soda.  This generally causes my DIY yeast to last about 
3 weeks, although I've had one going for over a month!