I have a Pentair Sta-rite SLE-L that I think pumps around 11-13 gpm and the high and low pressure settings are at their factory settings of 50-30psi, respectively. After replacing a number rainbird sprinkler heads and spray nozzles with hunter pro-spray prs-40 + MP1000 rotators, I am having trouble with the pump cycling on and off between the high and low pressure switches. I am only using the manual start on the controller for a single zone at a time to test for now since I don't want to risk the pump starting in the middle of the night and then burning up from cycling constantly. Zone valves are Rain-bird DV100's but nothing is special about them. I believe its due to inadequate flow out of the new nozzles across the entire zone causing too much backpressure on the pump. Other zones are working fine but I now have got two zones I can't use. Is adding more sprinkler heads the only way to control this or is there something I can add to the zone supply line to regulate the pressure? I would prefer not to add sprinkler heads just for the sake of adding sprinkler heads.