I live in the Chicago suburbs with a big yard. We have a sprinkler system on 6 zones. The back yard gets lots of sun. I start the system at 8Am and it runs every other day, per ordinance. There is a square section that is about 8x8 that is getting vry brown. It is clearly getting water from 2 differenct sprinkler heads. the majority of the grass is green. I have no clue why it is brown. Any ideas?