how to put enough water on sunniest part of lawn?
My lawn is a 40' x 68' rectangle, kentucky bluegrass. The edges/corners of the lawn are shaded half the day, so they are nice and lush. Center of lawn gets baked by sun all day, so it never looks nice. How can I put enough water on center of lawn, without overwatering the corners? I have Hunter PGP heads, and tried to find nozzles for center of lawn that have 20' radius and put out 6-7 gpm -- can't find anything close to this in any brand or type of head. How can I solve this problem? Would be easy to add a rotor in center of lawn from another zone, so center gets watered twice as much as edges. Thoughts?
More info: layout of rotors is typical, with head-to-head coverage, plus two rotors 15' apart near center of lawn. Soil is good, aerate and fertilize as recommended. Nozzles:
corners - #2.5 blue (2.5 gpm) nozzles
long sides - #4 blue (4 gpm) nozzles that rotate 180 degrees
center - #3 blue (3 gpm) nozzles for the two heads near center of lawn that rotate 360 degrees. Screw is way down in water stream to decrease radius to 20'.