I'm having some trouble with pressure in one my sprinkler zones and I was hoping someone here would be able to help me out. I have 4 zones with Orbit pop up heads on them supplied by a 1 hp Goulds well pump. Zones 1,3, and 4 all work normally and operate around 25 psi. The pump pressure is set up at 40/60. I've replaced the expansion tank, the pressure gauge, the pressure switch, and some of the PVC pipes on the supply side of the pump and the pipes coming right out of the pump. The reason everything looks brown and rusty is because the old expansion tank was leaking and spraying rusty water everywhere. Once zone 2 comes on the pressure drops to about 5 psi and water only comes out of the sprinkler heads in that zone about 5 ft. All heads operate normally and pop up and down fine. My father in law thought it might be the solenoid for that zone, so I replaced it with a brand new one, but it didn't help. The next thing we thought was there's most likely a leak in the line, however I have a city water spigot right next to one of the spigots I have hooked up to the well (I have 5 other spigots hooked up to the well around the house). Normally I just used the city water and hook a hose up from that spigot to the one right next to it for the well pump to prime it. So I thought I'd try and have the city water hooked up this time with zone 2 on and see how it works. When I did that the sprinklers worked like normal at about 25 psi. So because of that I feel like there's not a leak in the line, otherwise even with the city water going through the pump, if there was a leak it still wouldn't work (I would think). Does anyone have any ideas of what could be causing the loss of pressure? I just bought this house last year and this well was already here so I don't know the history of it, I just know the pump is a Goulds J10S. Not sure if it'll help, but I'll post a picture of my pump. I'm also new to all this irrigation stuff and don't know a whole lot of the lingo, so if you could explain anything in easier terms for me to understand I would really appreciate it. Thanks!