I know about all the fancy and expesive items many folks use with their CO2. WHen I got mine it was about 2003 or so. I am space constrained and somewhat cash short back then and I set up my system as follows/
CO2 Bottle with dual gauge regulator bought from a bee supply company.
CO2 resistant tubing.
Clippard Needle valve
Bubble counter
I pushed thh output hose into the thhe ATI prefilter attached to the intake on an Eheim 2026 canister. I selected Eheim as they were/are the premiere canister. I knew that putting gas bubbles into a canister (or other filters) could be a problem, so I did not even consider another brand.
It took me a little time to dial in the correct bubble rate. I started on the low side to be safe. My KH was about 4.0 and my tap water was just over 7.0 by .2 or .3. I was prepared to add an airstone on a timer for night so I could keep a constant bubble rate and not worry about things in the dark cycle.
My first mistake wat that I did not use teflon tape on every connection and I managed to leak out a 5 lb cylAder in about 2 weeks. Thay ledd to my first algae outbreak. I fixed that part of things. The tank ran great from then on until I had one of the 4 power compact bulbs die. I had no replacements on the shelf and it took me over a week before replacements came. The algae outbreak that time made the first one look mild.
I ran that system for almost a decade and it worked perfectly for me. But I found myself spending more time pruning and replanting on that tank than I spent on any 3 other tanks combined. I realized that I was a fish keeper not and aquatic plant keeper and my time would be better spent on fish than plants. So I sold the entire system for $150 used. I upgraded the tank from a 50 to a 75 gal.
I still had that Eheim canister running until this year. It was as quiet as the day I first put it into use. But my reducing my tanks load by a lot meant that canister and the 75 the caniister was on went out of use. I stile have two more of them running though.
I was able to graw any plant I wanted and that tank was my pride and joy until I had to abandon it. What I learned over the years was that all the fancy equipment and so called plant supplies were pretty much a waste of money as I needed none of them and I di great with my system. My bubble rate was 1/second 24/7. That tank was the healthiest one I had. Over the decade I lost almost no fish in it at all. It was where my Farlowellas spawned.
As always, the above was how I did things. They great worked for me but my way is just that. There are many more expensive and complex ways to do pressurized CO2 that can work as well. I just never had to try any of them. I replanted it a few times.