Well i dont run a CO2 setup myself but looking at others threads that do it seems to do wonders.

My local hydro shop tells me it increases yeilds up to 50% (but hes selling it so no-telling if he is exaggerating.

The only advice i can give (because i dont run one) is that you should get a controller.
Its expensive, which is why i havent gotten one yet, but its to make everything simple and it does everything for you, it will adjust itself and make everythingg much easier.