I run 31 ppm via a pressurized setup with a homeade reactor. I find I get stronger plant growth and less algae with around 30 ppm of CO2. And of course it's no danger to fish.
Just curious where you find this. I am fairly newe to Planted Tanks and yes I see that many people keep their CO2 in the 25-30 range but every and I mean ever article you read about fish always saw to keep the CO2 under 20.
Please understand I am not picking on you floater, I am just looking to sleep better with my tank because I do like my fish too. Thanks