How do you figure your right bubble count , how do you know if you are injecting enough or not enough ?
very simple, if i dont have algae and the plants are healthy and growing, it's the right bubble count. If i see algae, i adjust accordingly (usually increasing co2 as i like to start on the conservative side).
It's really not difficult to find a balance in freshwater, just 3 components: light + co2 + nutrients. Light is usually a constant for me around 3wpg, so comes down to adjusting co2 and nutrient (3x macro + micro + iron). Rex has a very handy algae guide to help you pinpoint the imbalance: http://www.rexgrigg.com/Algae1.html
I dont need some color chemical (that looks green, but also blue, or was that yellow?) to tell me how to adjust my co2. Not to mention it's 1 extra piece of artificial item in your tank to look after...
To clarify not saying those who are using it are wrong, if it works for you great, whatever get the tank to work! But for myself, i think it's useless and dont need it.