New to this forum, trying to hold back....
I still have not gone with a pressurized CO2 tank quite yet. I have been spending my money on new donated aquariums, better ferts, better fish, better plants, better lights ( My hobby only gets so much money per month. )
I have Aquafina bottles, 2 Liters, Juice bottles, all doing CO2 injection, some have diffusers, some have the "chopstick" wood thing, others just have a regular air stone injecting CO2.
I use the "Red Star Campaign Yeast" packets that I purchase locally for $0.50 each. I usually slap a $5 bill down and get my fix for the next few months. I always start all of my mixes with one Teaspoon, but culture them in the bowl with a mixing fork for longer per the size of the container. My nano gets cultured for like ten seconds. The larger mixes get bowl mixed for over an hour. Then I dump the culture into the mix bottle and let it crank overnight. I think it is always best to mix a new bottle up at night, so that when morning comes, the mix is at its best production (don't mix in the AM times when your plants need the CO2 saturation).
Place your CO2 rig against the tank and add some kind of insulation on the rest of the bottle to keep it going as long as it can. I use a terri-cloth towel with a rubber band as an insulator. It really helps after the first five days. So, your DIY CO2 is touching the tank for heat conduction, and the insulating towel should keep the yeast around at least 70 deg, even in winter.
** Editing again, Sorry.... Well, I have city water with only chlorine from tap. The whole boil everything and sterilize everything method only adds a day to your CO2 injection and takes so much time and effort, I could see how people don't do DIY CO2. Clean your hands really well with the most mild soap you have and don't use any kind of hand lotion. Don't use anti-bac soap, it will destroy your DIY CO2 no matter what you think. I only rinse my bottles out with hot tap water and then remix and put them back into production. **