The ON/OFF are for the controller to mimic low and high tides more accurately. If the setting is OFF, then there are exactly 2 tides a day. If you turn it ON, then the controller offsets each day by adding 48 minutes to the preset loop which creates a set of low and high tides that are more close to what happens in nature. In nature (because of the moon's rotation around the earth) the two tides are not exactly synced with the day but instead are a little offset.
In summary, Maxspect is just trying to give customers the option to have flow that closely resembles nature.