What kind of sand can you put in a pool filter?

Question

filter is an inground granular filter

Answer 1

Play sand is a no no. It's too smooth and usually smaller than 40mm. You need to use a sand grade like  #20 silica. It's rougher and has a slightly larger diameter. Both of these qualities are needed for the sand to do it's job. Smaller particles can pass through the laterals at the tank bottom ( you don't want that to happen) and smooth particles don't filter as efficiently as jagged ones.

Answer 2

Screened and washed playsand, found at any home supply center in the garden department. (Home Depot, Lowes, Menards etc..)