Galaxy Universal Systems ordered a custom programmed timer DC-10T-DN that could control the activation of the pump on their filtration system. Integrating it into their control panel, they wired in a push button to set the hours (20 Hours max.) and a start button to start the countdown timing sequence. While the timer is counting down the onboard relay would energizing a larger relay to control the water pump. Should there be an issue in the system a sensor would trip and open the latch on start, pausing the time. This would allow the operator to know how far the system got, correct the problem and resume.

Modified List:

DC-10T-DN ( Less Case, less push-buttons)
1.0 Inch LED Digital, Push-Button Controlled, Countdown Timer
Modify the above display to have terminal strip for Start, Hours, Zero Reset
Limit Hours count to 20 

Modify Start for start on closure, pause on open
Colons pulse while counting
Customer supplied 24VDC
Add onboard relay
Relay active while counting, off while paused