Was at a job yesterday that had I-20's (5 per zone) that ran fine, and it had 8 zones of 12" sprays (avg. 10 per zone with 10 & 12' 180 degree nozzles) anyway the rotors worked fine but none of the sprays would come up unless you turned half (5) of them off. So I figured that I had two choices: install pump or mp rotators and with 83 nozzles the price was a wash except I could get mp nozzles in the next day instead of trying to schedule the plumber to install a pump. So we tried the mp's on the furthest zone from the poc and BINGO we had a winner. I am now an OFFICIAL fan when needed they are priceless.