Controlling PH in a CO2 tank..

Hello guys.. I have recently added a yeast powered CO2 generator for my 16 gallon... But everywhere I am reading that having CO2 in the tank is goign to lower my PH.. they refer to using a Buffering agent.. to keep it stable so that it doesnt go up and down with the different CO2 levels.. my question is you guys say that you do not like those "ph up 7.0" formulas because it flucuates.. however if I have co2 should I start using this stuff?? My PH is already low.. I have done a few water changes and gotten it up to just below 6 but i cant for the life of me get it past 6... do you guys have any suggestions?? I have .1 ppm of ammonia and very mimimal nitrite and nitrate.. with 2 otocats one gourami in the tank.. thanks guys...
oh yeah its a planted tank as well.. probably 10 plants already

 

I don't have any experience with CO2, but I do know that crushed coral is a good buffer.

Also what are the exact readings for nitrIte and nitrAte? Any amount of ammonia & nitrIte can cause problems (especially for delicate fish like otos) so you might want to do a couple water changes to get those levels down.

-Chelle