You might try a maxi jet for a power head. A 600 or so will run a 100 gallon tank with a 12" reactor.
You can hide the pump with plants or add/glue cork to the pump and add java fern etc so you do not see it.
Some folks like to add the CO2 to their canister filters or use that same line. I like mine separate since I turn the CO2 off at night by plugging the powerhead into the light timer.
You can do both with the canister if you also have a solenoid. I'd get a check valve also if you plan to run the CO2 through a line like that.
I got the Aqua Medic regulator from Robert. Never had to adjust the output because it worked perfectly right out of the box. In fact I don't even know what it is. It must have been factory adjusted for aquatic use.