ET is calculated and sent to the controller every night at 11:50 PM. If the controller is programmed to start prior to this time, the ET will be calculated based on a partial day (not a full 24 hours). This scenario sometimes creates a low ET value that does not meet the Minimum Deficit ET setting under the Advanced Menu. An ET value that is less than the Minimum ET value therefore will get “rolled” over to the next scheduled irrigation cycle and the program will not run. This scenario also occurs shortly after rainfall events.