found this:
Some dual speed pumps have a toggle switch in the back of the motor to change speeds manually, but many do not. Generally you would need to tie this dual speed pump into one of our dual speed pump timers/controllers. One of the more popular models is the Digital PE153 series. This timer has 3 functions: one to turn the pump on and off, a second auxiliary to switch from high speed to low speed, and then a third for any other piece of pool equipment. You may view these controllers through the following link: Intermatic Timers