Timers can play an important role in a hydroponic garden. Depending on how your garden is set up, a hydroponic timer could be used to control several different aspects of your hydroponic garden. Most often, timers are used to control the light. Using a hydroponic timer allows you to set up a perfect lighting schedule, turning lights on and off at specific times. It can also be used to control when and how often ventilation (fans and filters) turns on and off. Also, it may be needed to control the nutrient flow intervals.