We recently bought a home that's about 30 years old. There are only 5 zones with a maximum of 3 sprinkler heads on each zone. Zones 1-4 work OK (plenty of pressure) and good rise and coverage from the popups. However zone 5 is driving me nuts. The pressure at the sprinkler heads is so low, that they just bubble. The valve seems to be working OK and turns on and off like it should. When I remove one or more of the sprinkler heads the water simply bubbles out of the tee. I use a 26VAC sprinkler co...
