CA reactor pH range: how to I narrow it?

[Wrasse-cal]

All,

How do I get the pH range of my reactor to be tighter? Right now, my reactor pH varies between 7.2 and 7.13. I've seen other people have basically no, or .01 variance.

I have a Geo 618 Calcium Reactor, 415 Secondary Chamber with Carbon Doser electronic regulator.

My Carbon doser is set to 8 seconds per bubble and 10 psi.

Per my Apex, I have my CO2 feed set to turn on if the reactor pH rises above 7.19, and off if the reactor pH drops below 7.16. I have a 30 second defer on turning on.

Can anyone give me some suggestions on how to tweak my settings? The reason I want to do this is I suspect my bouncing pH causes me to use more CO2, which depresses my tank pH.

 

[ndrwater]

You can SLIGHTLY increase the size of the portion of CO2 released by turning the large black knob on the Carbondoser to the left. It will allow a bigger bubble. Or... Decrease the time between portions.
Either way, you should keep an eye on your ALK for a day or two after..