“To get a rough idea of how much sand to apply over the course of the year, we have developed a simple spreadsheet that uses growth potential (GP) as a guide, and a maximum sand application of 150 lbs dry sand/1000 ft2 per month at maximum turf growth.”
That maximum rate is about 0.5 mm per month, and it is based on the rates used by Hempfling et al. in their research about topdressing and anthracnose.
In the spreadsheet, one can adjust the maximum rate. I left the maximum rate at the default setting and entered temperature data for Bangkok. That gives a total annual topdressing amount of 1,656 lb/1000 ft2, or 5.4 mm. Seems like it’s in the ballpark.