because it will stabilize your ph. At night your ph drops and when the lights come on the ph rises. people run reverse lighting to keep it more stable. Also a lot of people leave their fuge light on 24/7 to accomplish the same goal and to keep their macro from going sexual. HTH
I wouldn't expect much different in your pH. The amount of life in the display tank making CO2 will likely be many times more volume than what you have in the refigium consuming CO2.
A kalkwasser drip at night would make much more noticable difference. I have my refugium lights on 24x7.
