never heard it called that? just by a co2 burner or a co2 tank and run it when the
lights are on. very good growth i do it the winter when its easier to control the green house temps so i dont ahve to blow it out. but my new green house has ageo metor engine that runs on propane and it will feed co2 as well as back up the greeen house whe teh powers out and keep my heated floor warm.