Any DIY CO2 bottle is capable of generating enough pressure. The problem is that the bottle isn't strong enough to withstand the pressure. If you can use a strong juice bottle, with a good cap, with the outlet tubing well secured you should be able to hold the 2 to 5 psi needed. But, a failure will blast yeast and water all over the place, and possibly let the tank water siphon out. So, if you enjoy taking risks, enjoy!!