I got mine from a welding supply. Aluminum is nice because it is light. I have one of each and there is a difference, although it is not a deal breaker if you can only find steel.
is a common regulator setup. I use this on both tanks and have been quite pleased. If you want to go one step further, you can purchase a pH controller that shuts off the co2
when pH gets too low. I don't use a controller and just cycle the co2
with my lights... So far so good.