I got a brand new 5lb aluminum cylinder filled with food-grade CO2 from a local welding supply store. Now that I own the cylinder I can trade it in for a refill for about $20. But I expect this one to last around a year unless I start going soda-crazy.
The assembly was pretty straightforward: screw the regulator onto the tank, and slip the hose onto the barbed output of the regulator. I put the end of the hose into hot water for a minute to soften it up, then lightly tightened the hose clamp onto it.
I always keep the valve on the tank fully opened, but when not in use I close the output valve on the regulator. That seems to strike a good balance between convenience and not losing CO2 to leaks.
I’ve accumulated various sizes of plastic soda bottles that I re-use. The process is pretty simple:
Mix your drink, chilling it as cold as you can. Cold water absorbs CO2 better.
Fill the bottle, leaving a few inches at the top to make agitating it more effective.
Squeeze the bottle so that there’s almost no air left at the top, then screw on the carbonation cap.
Open the regulator valve and set the regulator to 32-40psi. The ball valve will prevent gas from actually coming out until you connect it to the cap.
Connect the ball valve to the cap and agitate the bottle for about a minute. I braced for an exploding bottle the first few times I hooked it up, but no disasters so far.
Let the bottle sit pressurized for another few minutes. This can be with the hose still connected, or the cap should maintain pressure even when disconnected.
Open the bottle and enjoy your DIY soda!
I’m still experimenting with recipes and such, but a few things I’ve learned so far:
The biggest challenge for me is getting the carbonation to “stay.” It’s almost always well carbonated right when I open the bottle, but often if I leave a glass out for over 20 minutes or so, it’s mostly flat. A few things mitigate this problem: keep the water as cold as possible; avoid carbonating liquids with particulate like fruit pulp; and using clean bottles and glassware. Not sure if there’s anything else I’m doing wrong to cause this problem.
I find most flavors taste better with at least a little sweetness, even if it’s not traditional soda-level sweet. I mixed up a batch of simple syrup and toss in a few teaspoons before carbonating.
Certain flavors come out more after carbonating and others seem to get overshadowed. Luckily this process is ideal for micro-batches, so iteration is cheap and easy.
I also just ordered Dave Arnold’s Liquid Intelligence, which has a whole chapter on carbonated drinks. So I’m sure that will yield more inspiration.