CO2 Controller and Buffers

I just switched from a timer-based CO2 system to a CO2 controller. I was
getting a wide fluctuation in pH from 7.6 in the AM before the timer started
to 7.0 at the end of the lights-on cycle. Now I'm in the range of 6.9-7.1.

I use RO water and just switched from Kent's RO Right to Seachem's
Equilibrium. I also use Kent's pH Stable. I'd like to keep the tank at
about 6.8. I see that there are buffers available that claim to stabilize
the tank there, but I've not had any experience with them.

I do about a 40% weekly water change and bubble the CO2 at a bubble a
second.

Is the combination of Equilibrium + pH Stable the correct way to go?