When you start injecting the CO2 into the tank, the pH will start to drop. You can certainly get some plants to grow with no CO2 and a pH of 8, but not likely a lot of them. But, now that you have the controller, why would you not want to start injecting CO2?
Oh, and what's so special about a pH of 7.0? I know when I started my first tank, I was pretty obsessed with hitting a pH of 7.0. But, there's not really a good reason, IMO, for doing this. What's your reason for choosing 7.0?