Hello Laurie.
In my experience, pressurized CO2 is your best option. It is really helpful to have a high water circulation rate (around 10X an hour), a good needle valve (I've only learned this since getting my paintball system with a high-end needle valve), and a good diffusion method (reactor, atomizer, ceramic/glass diffuser) preferably in that order for effectiveness. The reactor/inline atomizer can be plumbed into a canister output line.
Best regards,
Stuart
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