Will I have to raise the KH or GH of my water for CO2?

My new tank set up has a KH of <1 dKH and GH of 3.

I am going to be setting up a pressurized co2 system and am a bit concerned about my water quality. Should I buffer my water a bit and if so what is the best /easiest/most reliable/stable way to do this.

Thanks.

Oh, the pH is 6.8 if that's any help. If I use the KH/pH chart for dosing CO2, I think I would need only to bring the pH down to 6.4 to get 20-30ppm. I may not need a lot of Co2 if that's the case.

kara