If you want to include a meditative sand feature in your Japanese zen garden, not just any sand will do. Actually, instead of sand, use fine gravel for your garden.
Raked gravel is less vulnerable to the elements, especially wind and rain. If you use regular sand in your garden, you put all of your careful preparation at risk of washing or blowing away.
Reach out to your local landscaping supplier and ask for gravel between 1/16 and ⅛ of an inch across. These pebbles are the perfect size for raking but heavy enough to stand up to the elements.
For indoor zen gardens, though, sand is a fine option. You can even use colored sand or gravel, like you would find at a local aquarium store, to create a one-of-a-kind look.