Succulents don’t like to have their roots sitting in wet soil, so it’s important to add sand or pumice to your soil mix to improve drainage. Other nonorganic materials that will help to loosen the soil include perlite, small gravel, crushed granite, or Turface (a calcined clay product).
“We like to use volcanic sands (pumice and scoria) to keep the soil from being too heavy, but regular sand is OK also. Most commercial mixes lack sufficient sand component because of shipping weight issues. About 60% nonorganic and 40% organic material is what provides good drainage and permanence,” says Jesch.
Website: https://www.succulentsgreener.com