and to reduce clogging of plant roots, which
could lead to loss of crop productivity.
Our aquaponic system established in Waedenswil,
Zurich, was a new concept using lightexpanded
clay aggregate (LECA
TM
) [13] as filter
medium for the trickling filter. LECA is a type
of clay, which is super-fired to create a porous
medium. It is heavy enough to provide secure support
for the plants’ root systems and was used in
indoor and outdoor hydroponic systems [13–17].