The optional Night Mode Adapter plugs into an Apex controlled outlet -OR- your own mechanical/digital timer that you can set. It will allow the option to shut off the CRTT reactor at night. If the reactor is running fairly hard and producing a lot of effluent, that can lower the PH of the aquarium system. Some aquarists will then use the Night Mode Adapter to cycle the reactor off at night when the PH is the lowest in the aquarium and then compensate for it.
When the outlet is energized (nigh mode on) the waterflow pump will not cycle. If you run the night mode adapter from 11 PM to 6 AM, the unit will only recirculate and keep CO2 saturation during this time. No waterflow pump activation so no effluent out of the reactor. To compensate for this time off, you need to double your waterflow/24hr and degas amounts.
For example, if your waterflow/24hr is at 20 lpd, and your degas is 20 lpd (as these two values should match) with the night mode on for 8-10 hours, you will need to set your water flow at 40 lpd and degas at 40 lpd to get 20 lpd output. This is because the CRTT smart controller divides the total water flow into 4 doses daily. With the night mode adapter, it will skip 2 doses.
( Note: The night mode adapter plug will stick out close to 1/4" where it connects into the controller - this is the proper installation and it will not push in all the way. )