Actually I am not the best person to ask since I don't have any personal experience with CO2 or ferts......I have natural soil based systems and they create everything that is needed.....
But I do know that the ferts are designed to be safe with most fish and livestock-some can cause problems with some inverts.
With CO2 you need a lot of light and generally with Betta the CO2 will not cause problems-but other species it can if you are not careful as posted by battered and as Twilight storm posted you may want to go to the plant section on TFK and ask.....
Sorry I couldn't be of more help....