I have a system running on our home well. The main feed for the irrigation system runs off of the main pump line, just before the pressure switch/pressure tank. There are 14 zones, with from 5-8 heads on each zone. When I turn on a zone, the heads pop-up fine, with full pressure. However, after about a minute, the pressure drops down, causing some of the heads to go back down, due to lack of pressure. After about 20-30 seconds, the pressure kicks back in, and the heads spray at full pressure. The cycle then repeats itself. This happens at all times of the day, and when there is nothing else drawing water from the system. I'm running a Hunter ICC controler, Hunter I-20 heads, and rainbird valves. As far as I can tell, the cycle/soak is not turned on. (I'm not sure if this is what happens in that mode) Any ideas why this is happening and/or suggestions to fix? Thanks, Brent.