To my understanding a DE filter can run on a timer but a sand filter usually should not because it doesn't filter as well as a DE and should run 24 hours a day especially in hot weather.
I was just considering going to a two speed pump to both clean the water more efficiently on low if I am understanding this whole thing correctly and save on my electric bill in the process. To my understanding the high speed is only needed for a high bather load, to back wash and for sweeping. I am not sure when I order a two speed pump if the pump itself has a switch to go from low to high or if I need to order a special switch and wire it accordingly. I was just hoping someone with a two speed could tell me how they like theirs and how the switching works. Is yours a two speed?