You asked for them, so we found them! 

Use these sinking beads as a replacement for sand in sand filters, or use them in a fluidized bed or as inert hydroponics media. 

These beads come in assorted colors (no choice) and are sold per cubic foot. 

Weight is 45 lbs. 

Dimensions are typically 1/16" x 1/8" in an oval shape. 

When used in sand filters, backwash water flow should be reduced, as beads fluidize easier than sand. 

Beads have a specific gravity of 1.7 (sand is 2.0 to 2.8).