Is there any benefit to the fish or plants to have a bubbler come on over night when the co2 is off? wasnt sure if the bubbler would help correct the PH and help the fish when the light and co2 are off
In tanks with a lot of fish load and with high coverage of the tank surface by surface plants it can help a lot in keeping the oxygen levels up during the night. It will also remove the residual CO2 from injection so you will have to inject more the next day to make up for it .
Most tanks with normal fish load a clear water surface with some rippling from the filter outlet will likely not see a big benefit.