Calcite is crushed limestone and is a sacrificial filter media that raises pH.
A gravel under bedding is required.
If your tank is 9" diameter x 48" tall, it holds 1 cubic foot; 10" diameter x 47" tall, it holds 1.25 cubic feet; 10" diameter x 54" tall, it holds 1.5 cubic feet; 12" diameter x 48" or 52" tall, it holds 2.0 cubic feet.
