I found it easier to judge reactor settings by how your tank water reacts rather than what comes out of your reactor. I tested alk every couple days. If my alk dropped, i slightly increased co2. If alk increased, i left it and kept testing every couple days until it stabilized on its own. If alk kept rising beyond where i wanted, i slightly decreased co2 output.
With this method I quit testing the reactor output parameters and had it dialed in within 2 weeks without a bubble counter
Good luck!