Help!!

[shadetreelawns]

I service a HOA that the irrigation system is on a well. I am constantly having spray heads that the filters are stopped up. Most of the spray nozzles Hunter Pro sprays and I have tried some MP Rotors. I will remove the nozzles and they are covered with dirt/sand. I will turn the system back on with a nozzle removed and I will get a clump of dirt shoot out of the head. What can be done about this? Is there a filter that can be placed on the pump? What other suggestions do you have? Thanks