You are getting things mixed up a Par meter is used to see how strong the lights are in a tank.
Watch George on how to set up an run a Co2 system.
I understand what a PAR meter is... I had one many many years ago.
But isnt the amount of CO2 based on your lights?
More lights = more CO2 = more ferts? all dependent on plant demands?
That is the way I understood it.
Edit: That video doesnt answer my question... If I wanted a full large CO2 system, then OK. But im using what I have, and trying to ensure it works the way I want before I upgrade.