I see a few problems.1 you should not use sch 40 pipe for your irrigation system because the preasure loss is to great.The maximum flow in 3/4 sch 40 is 8 gpm and you loos 10.8 psi per 100.You may need to go to class 200 pipe so you can run 10 gpm and only loose 4.3 psi per 100.also if you have low preasure to start be sure to center valve,also a loop main line can help alot if it is possible. good luck
