Re Maxijets - compare the wattage flow of the 900s to the 1200s and the 900s appear to be much more efficient. (That said, I run 1200s myself...)
Re Powersweeps - these just simply do not work over time. They might run for awhile but they will quit sweeping - its just a question of when. Also they are very large / bulky compared to the MJ and more expensive. I have 2 of the 228s and I can't give them away.
As to how many you need? 65x10 = 650gph total. 1300gph even better.