I question what is the point of injecting an absolute maximum possible CO2? I know it's highly popular and the majority of people focus on how to get the absolute max in there, many stating similar - go until you see your animals gasping then you know you are just above "optimal levels".
I have mine set to a .8pH drop vs 1.2pH because (1) I don't like stressing animals (or taking the chance), (2) I also use Excel so plants get some carbon from that, and (3) My .8pH drop (maybe 20-25PPM CO2) results in ridiculously fast plant growth. I have to trim weekly or the tank will be in a bad way. I can't imagine running that even faster, I would have to trim every few days.
Is there more to maxing CO2 than just plant growth? For example will some plants grow in a more desirable way (e.g. shorter, better colors, more carpety ... ) if CO2 is @35PPM vs 25PPM?