I am a homeowner and I am having problems with the pressure on my home irrigation system. My well is only connected to my irrigation system and it is controlled by the sprinkler control box. I replaced the box about a year ago because the first one was damage by water getting into the box during the 2004 hurricanes. About three months ago my well started to fluctuate the pressure in the system during watering. At first it didn't happen every time and when it did it may not happen through all of the zones. The fluctuation was accompanied by a loud thumping noise in coordination with the water pressure fluctuations. I just figured that we were going through a drought at the time and the water table was low or something. Now it has gotten worse. The thumping and the water pressure fluctuations happen every time consistently. We have gotten tons of rain so I know that isn't the problem. Also, now the thumping happens when the well is supposed to be off between watering cycles. About every 10-15 seconds the well does a single thump. I have looked at the pressure gauge when this happens. The gauge shows 90 prior to the thump and 100 after the thump. It then slowly goes back down until it reaches 90 again and the well thumps again. I have also noticed that this is what happens when the system is running as well. If when the system is running I open some of the pressure release valves on the well and let some of the water out it starts to thump faster until the pressure drops below 80 and then it stops thumping and the system runs fine with no pressure fluctuations. I am trying to find out if this is something I can fix myself since I am very mechanically inclined or if I really need to call in a professional to do the work. Any help would be appreciated. P/S: The well is about five years old.