Help with mixed use low pressure system
This is a drawing of my backyard. I hope to explain everything in enough detail so I can get some solid info.
Weather data: http://www.idcide.com/weather/wa/kennewick.htm
88 psi (this year) from the irrigation main. Generally, it's right around 85 psi.
Under the 11" tall, 8 sq ft. raised beds is pea gravel (1/4" round rock), and under/around the trees is hemlock bark mulch. The valve box in the corner spits out two 1" PVC lines running along the property lines on three sides.
Along the bottom is what I call "The Island". It's surrounded by grass, house, patio, and path. I currently irrigate TI by turning on the hose bib. Out of the HB, the city water goes straight down (through a 25 psi reducer and a fancy union fitting) to buried 3/4" PVC lines that come back out of the dirt and feed flexible poly tubing, and finally to 1/4" drip line. They pop up in about eight locations. Based on the plants water needs, there is either an open 1/4" tube, a shrubbler, or a microsprayer. All plants are well irrigated, but we chose more drought resistance species. That section runs five minutes per day at most.
The raised beds all have drought resistance species and only shrubblers. Every two beds are fed from a threaded PVC saddle connected to the 1" main line, 25 psi pressure reducer, and poly pipe into 1/4" drip line. Most have three shrubblers. They are running at nearly no flow, and are set to run fifteen minutes, three times a day. Healthy plants in there.
The trees are also set to run fifteen minutes, three times a day. They each have their own saddle, 25 psi pressure reducer, and short poly pipe into 1/4" drip line. All six trees have "tree stakes" at the root system. 12-20" long PVC stakes that have 2gph shrubblers stuffed down to the bottom running wide open. Each tree also has a wide open shrubbler at the root base.
Finally, the questions!
What is a good way to start irrigating The Island using the irrigation water based on how the timer is currently set? I was thinking that anything in TI would need to be REALLY set to almost no flow, based on how it's irrigated now. Or do I add more lines to the trees and adjust the time down?
Switch to super low output microsprayers for TI?