If your output isnt that great it usually means you have a small or big leak in your system somewhere.Check connections carefully. ;-))
here it is i found it. if you look under application on this thread a little ways down it says what the OJ and other stuff is used for, its a pretty in depth explanatory article
http://www.aquariacentral.com/forums/showthread.php?t=152401
I think a lot of DIY CO2 success comes from the type of bottle.
I use heavy duty (AriZona ice tea) plastic that has a screw on cap.
I drill a hole in the cap that is smaller than the OD of the tubing. Pull the tubing through the hole with some long nose pliers. Then I use a recipe similar to the one Trigger uses.
However I do add about 1/3 tsp of baking soda. The more sugar and yeast added = more vigorous CO2 production.
IMO, the flimsy soda bottles expand too much to force the CO2 through the diffuser.
I also hook two bottles in tandem and change one each week. The color in my DC’s stay at a yellowish green almost constantly.
Also, after I mix a new batch, I put the whole bottle in the sink with warm water for a couple of hours. This gets the mix generating CO2 before I hook it into the system.
In colder weather, DIY CO2 is harder to start.
Before I started pressurized on my 46 gallon, I used this method of DIY successfully. Pressurized is a lot less trouble.
Good luck
Charles