If anything you should have raised the mower. Going that short would be one mistake.

Watering every other day for hours is probably too much. Certainly it is too often and if your watering system is working at all, then you are overwatering the snot out of your yard. With that in mind I am going to suggest that you might have a fungal disease caused by the yard being continually soggy. I have a home in San Antonio and one much further out in the desert. As of this month I do not have a regular watering schedule yet. The desert house has received about 4 inches of rain this year but spaced just about perfectly. I have watered parts of the yard once or twice but most of the yard has not been under a sprinkler yet. In San Antonio we have received 15 inches of rain. We are just now getting ready to go to regular, once per week, watering.

Everyone's watering situation is different, but not by much. There are about 10 different factors to consider, but it is much easier to look at the grass and let it tell you when it needs water. You'll see a darkening as the blades fold together. Then it is time to give it a full inch of water more or less. Whether it is more or less depends on how long the grass goes before it needs water again. If the temps are above 90 then you should water once per week. If the temps are between 80 and 90 you should be able to go every 2 weeks between watering. If your grass tells you it needs water before the suggested time is up, then water immediately but water for a longer duration. Soon you will get into a groove with that.

The only thing worse than watering every other day for hours would be watering every day for hours. Even watering every other day for 10 minutes is bad. It is much better to apply a full inch all at one time and then let the surface of the soil completely dry out before watering again.

Back way off on the watering, as much as Mother Nature will let you. Then see if the spots get better or worse. Assuming they get worse you will need a fungicide to stop the spread. I am not a fungicide kind of guy but I have seen Immunox mentioned by Tiemco on this forum. Read the label carefully for the weather conditions needed for proper application. About 3 weeks after you are convinced the fungus is gone, then you should reintroduce the beneficial fungi back to your soil which the fungicide knocked out. The best way to do that is with compost applied at no more than 1 cubic yard per 1,000 square feet. That is a fairly light dusting. After you apply it as evenly as possible, use a push broom to sweep it off the grass blades and lift them up out of the compost.

Don't apply lime unless you have a soil test that tells you it is deficient. There are two kinds of lime so the test needs to tell you which one to use and how much.

Hey there, I wonder if you have a pet whose urine is killing the lawn, to get round this I have used Dog Rocks (www.dogrocksus.com) for the last 6 years and they are EXCELLENT, safe and 100% natural, good luck!

Here is a link that might be useful: Dog Rocks

These look to me like dog pee patches - they are just what we had on our grass last year - we use dog rocks now and have a lovely green lawn - to our relief! We got them from amazon.

Nice looking lawn either way. Good job ;)