You will have to individually dig out weed grasses. Kill broad leaved weeds with a Weed-B-Gone herbicide product made for St. Augustine. (Be sure to read label.) Do not let it get so far out of whack as it gets exponentially harder to bring back under control.

Where do you live? I ask that mostly because if you live in FL you're going to have to come to grips with neighbors telling you how to water.

You are watering wrong. I have only watered my St Augustine lawn one time this year. Last year we had more rain and I didn't water until June. That year I watered a total of 5 times. Year before that we had better rain and I did not water until July. That year I watered a total of 4 times. You should NEVER (ever) need to water every 2 days. Clearly the grass is established and happy with the incorrect watering, so it will take just a little weaning to get it where is should be. Ideally in the hottest heat of summer you would be watering once per week. Here's the entire watering guidance that should work for St Augustine anywhere from Phoenix to the Everglades. Deep water every time. Deep means 1 inch all at once, not spread out over several days or twice a week. Set out some tuna or cat food cans and time how long it takes to fill all the cans. If you have dry spots in the middle, be sure to put cans there. That time will be your watering time, every time you water from now on. My watering time with an oscillator sprinkler, my water pressure, and my hoses is 8 hours. Yours is going to be a lot less with an in-ground system. It might be as little as 20 minutes. With temperatures below 70 degrees F, deep water once per month. Mother Nature usually takes care of this at those temps. With temps between 70 and 80, water once every 3 weeks. With temps between 80 and 90, water every other week. With temps between 90 and 100, water once a week. With temps from 100 to 110, water every 5 days. With temps from 110 to 115, water every 4 days. This is guidance, not gospel, but it's much closer to what your lawn needs than watering every other day regardless of anything else.

Are you doing your own mowing? If so set your mower to the highest setting and mow every week.

Get ready to fertilize for the first time in 2 weeks (Memorial Day). If you want to use organic fertilizer, let me know where you live and I'll help you get the right stuff.

Do you have weeds in the lawn? or just at the edge? Pictures, please. If that second pic is the same area as the first pic, then run to the store to get some of this stuff. It should kill most of the grassy weeds and the broadleaf weeds.

And tell us where you live.