Hydroton is a brand of LECA, or Light Expanded Clay Aggregate. It has been kiln fired to increase durability. Hydroton is a very lightweight option for creating a false bottom, creates a void for excess water to go (so it does not saturate the soil layer) and also acts as a drainage layer. It wicks water slowly back into the substrate, allowing for a more humid environment. Hydroton also provides a large amount of surface area for beneficial bacteria to grow. These bacteria will work to metabolize wastes from the system, resulting in a cleaner environment.