[url=https://plantanswers.tamu.edu/turf/publications/staug.html]St. Augustine Grass[/url] information.
[url=https://www.american-lawns.com/grasses/palmetto.html]Palmetto St. Augustine[/url] information
St. Augustinegrass tolerates a variety of soil types, but let me explain soil a little bit as it applies to your question.
The term "sandy" indicates soil structure for the most part. Sandy soil could but doesn't necessarily determine whether grass can grow in it. Ideal soil structure is called a loam, which is comprised of clay, sand, and silt (and organic matter). Sometimes, a good loam is referred to as "sandy loam" which is perfect. Is that what you mean, or are you saying soil is sandy and somewhat less than ideal? Just want to make sure you recognize the difference and haven't gotten confused.
Usually, the problem with sandy soil (not sandy loam) is drainage. Because there isn't enough clay and silt (and organic matter) to hold moisture, then water and nutrients quickly drain through - faster than grass has opportunity to become properly hydrated and nourished. So, you end up having to irrigate more often and probably fertilize more often too since nutrient cationing is compromised.
The really good part is you are starting over, which makes it ideal time to incorporate other necessary components to improve soil structure. [url=https://www.lawnfertilizers.com/info/soiltests.html]This article[/url] will help you understand the ratio of components. First get a soil test so you know what you need and how much. Contact your local [url=https://urbanext.illinois.edu/netlinks/ces.html]County Extension service[/url] for test information and sampling instructions.
Here is [url=https://weather.nmsu.edu/teaching_Material/soil456/soiltexture/soiltext.htm]a neat trick[/url] to determine the pecentages of sand, silt, and clay in your soil.