You need to take a soil test first to figure out the underlying problem. Turf cannot grow in poor soil conditions no matter how much you water. Maybe you watered too much? This link should help you with the soil test. It's inexpensive and you'll have your results within a couple weeks. http://hort.ifas.ufl.edu/woody/ph.shtml
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. There is a ton of information out there for your specific conditions. Whoever put down the sod should have tested the soil and added whatever amendments necessary to balance the soil first.