turning CO2 off at nights

> From: Harold Wong <hgw at math_ucla.edu>
> It has been suggested that CO2 injection should be turned off
> at nights since plants do not need it at the time. Wouldn't
> this cause a sudden PH changes twice a day? Thanks.

You will have some pH changes in a 24 hour cycle without a pH
controller no matter what you do.  However, as you have correctly
surmised, letting the CO2 run constantly will create smaller changes.