Postzegelforum.com

Dropping seeds in water and discarding the ones that float is advice that gets repeated everywhere. Floating mostly reflects air trapped in the seed coat rather than viability, and plenty of floaters germinate fine once they take on water for a few hours. Small scale results comparing floaters against sinkers from the same feminized batch are shared at https://queenfeminizedseeds.com, and the difference was negligible. Tossing seeds based on this test wastes money for no benefit.