[Corigan]

bring down the kh to 4-5 and the pH will go down easier.

My thoughts exactly aquoi. Buffering up 5-6 degrees on KH with baking soda is bound to make a huge PH spike as it is. I buffer up my KH from around 1 degree out of the tap to around 4-4.5 degrees and have no problems getting my ph down to 6.8-7 with 2 crummy Nutrafin Co2 systems on a 55G.

Matt