The growing media in aquaponics system is dominated by clay pebbles, as they are perfect for the root structure and to maxmises surface area available for beneficial bacteria. Clay pebbles are the most common growing media in Aquaponics and are also known as clay balls, or Light Expanded Clay Aggregate (LECA). Often perlite is used in growing channels in aquaponics systems (inside net pots) as it is a cheaper media. Do our Clay Balls float? Canna Aqua Clay Pebbles are the best clay pebbles we have come across for their longevity and sinking ability. If you are using them for Aquaponics they are the best growing and filtration media in flood and drain beds. However, some will float if you fill the grow bed with water to the level of the clay pebbles, so aim for the water to fill only to within 2.5cm of the top of the clay balls. This prevents sunlight penetrating to the moist clay balls and create a green layer of algae on your clay pebbles. Also, if you wash the clay pebbles in water when preparing your media, you will notice that up to 50% of these balls float to begin with, but within a few days all will sink. This is much faster than other clay balls we have tested!