K....Ive made wavemaker controllers in the past. The koralia pumps arent the best pump for the aplication, however thats what I used at the time. Ive never heard of them burning out from turning on and off. The older ones do have a minor issue of sometimes turning on backwards, hence the banging noise sometimes heard when they are turned on. I found if you put a small piece of airline tubing on the shaft between the impeller and the front of the powerhead it dampens the noise considerably.
There are many ways of controlling power heads, you obviously dont want to go the controller route..there is a decent low tech solution though. all you need is a low speed motor(60-120rpm) can find them in most surplus stores, some spdt's or to make life easier some dpdt's. kind of hard to explain but ill give it a shot. You mount to motor to some sort of box, piece of wood...doesnt really matter, just depends on how you want it to look, and if you want it water proof or not...(aim for water proof imo
) put a cam (picture one of the lobes on a cam shaft) on the motor. Now around the cam, mount your spdt's, or dpdts equally spaced. if you need to control 6 powerheads, then I would recomend 3 dpdt's as opposed to 6 spdt's. then all you have to do is wire the spdt's/dpdt's to a common power, and to 6 separate outlets. and VOILA diy wavemaker.
note// make life easier and get 120v rated spdt's/dpdt's then you dont need any sort of relays or power supply.