I am having problems getting enough pressure to some of the zones on my sprinkler system that are far from the house(I'm barely getting 15psi, the close zones get about 40-45psi) and it is causing missed water spots in the yard. It's an acre yard and the farthest heads in question are around 200 ft from the water source. My source is city water but I have a pump connected to the line that runs when the sprinklers are running. The pump is a 3/4 hp jacuzzi jet pump, 3475 RPMs, made in 1989 (that's all the info I can find on the unit). If I turn the zone off but leave the pump run, I get about 60psi. I'm guessing that this pump was probably originally undersized (I've had missed spots ever since I bought the house 5 years ago but had never checked the pressure) but I'm not going to pretend to be an expert so that may be totally in left field. Is there a way for me to figure the correct size to gain more pressure for those zones. Thanks in advance for any suggestions.