How much Co2 to inject

Jose Guzman  asks: "How much Co2 to inject?"
the key is pH and I figure about 6.2 to 6.4 is about right. Some of the
others may have something to add to this. How many bottles and
bubbles depends on how big your tank is and esp. how much 
turbulence and air/water interaction you have and perhaps even
how many plants you have. See other posts.