I very recently purchased the Ultimate Misting system and thought that the ST-42 timer (included) was defective. I reached out to Mist King and was assisted by Marty. As it turns out, I was misinterpreting the programming instructions regarding "Start" and "Stop" times. It seems that the correct "Start" time should be the time that the misting system should turn on and the "Stop" time should be the DURATION that the the mister should STAY on. Each program (designated by p0 through p9) can be set to a different start and duration time (i.e., stop time). Thanks, Marty for patiently providing user training on this issue. The system is solid and we're very satisfied!