notoptimal's recipes sounds interesting. I might reconsider using diy co2 if I can get it to last about a month. Will a one gallon container with doubled the amount of your ingredients last me 6-8 weeks? Is the 3-4 week production period per 2L bottle? What does the beef boullion cube do? Can a chicken cube be used instead? lol Where can I get blackstrap molasses, does Publix sell it? Is blackstrap a brand or type of molasses? So you just sprinkle the yeast on top of the water and not shake it? Sorry for all the questions.
I don't know what the effects would be of scaling up volume. When I was informally testing recipe durations, I used 1/2 the listed amounts in a 1 liter bottle. From what I've seen, scaling up amounts and volume doesn't seem to affect how long the mix lasts, only the amount of CO2 being pumped out at any one time.
The boullion cube is in there as a protein source, similar to what the Nyberg (?) method uses the protein or soya powder for -- it gives the yeast the protein it needs to multiply (or so goes the theory). Chicken boullion cubes, or any other protein source in small quantities, should be good.
Blackstrap is a type of molasses, not a brand. Most supermarkets have the molasses either near the baking ingredients or the maple syrup.
As for adding the yeast, I've found that sprinkling on top and not shaking gets the mix going in about 2-3 hours. Completely mixing it into the water, even if well aerated, seems to slow the process down to overnight. By using the oxygen in the airspace of the bottle, the yeast "jumpstarts". When I used to mix it all in (by shaking after adding it), it usually had to sit overnight before it would start to bubble.
As for your green spot algae, CO2 won't help that from what I have read. You'll need to bring up your phosphate level to get rid of it.