Originally Posted by ray-the-pilot
CO2 = H2CO3= HCO3- = CO3(-2)
What this means is that any of these species will convert to the other and all are present in water. The amount of each depends on the pH and the amount of spectator ions like Na (referred to in aquarium literature as kH).
So when you add baking soda (NaHCO3) to your tank you are adding CO2 as well. In fact, one of the ways they make baking soda is by adding CO2 to a solution of Na2CO3.
Plants can crack out most of this CO2 and do so until the pH reaches about 8.4, which is the equilibrium point for the HCO3- = CO3(-2) reaction.
So when you add CO2 you are simply adjusting the relative levels of H2CO3, HCO3- and CO3(-2).
Ray, Since you have knowledge of organic chemistry, I'm wondering if you could answer something for me. Allow me to get off topic for just ONE question, PLEASE!?!?!?!.
Is this similar to what happens when sugar is added to a planted tank? Could it actually make CO2? (Not that I would condone this or practice it...just curious about something I read. )