So I have my regulator. The GLA Gro-1. And now I'm wondering what else to go with it. I have decided to put this set up on my 40 gallon and break down my 10 gallon. The 40 is medium light. I use an aqueon HOB for now as filtration. I was planning on renting a co2 tank from a local gas place. The regulator says it has a check valve as part of the regulator in the diagram that came with it. Do I need a check valve? I was planning on getting the GLA atomic diffuser that isn't the in-line one and has the check valve as well. Not sure what size I will need for a 40B. Any suggestions? What drop checker is good? I can't afford a pH probe at the moment. Anything else you can think of that would be helpful? Thanks!