These pots can then be filled with mineral wool hydroponic growth medium or expanded clay pellets. The plants really won't care which system you use, provided it gives them some support until they grow good-sized root systems.
Insert pots full of expanded clay pellets, shown at right, into the raft to fend off hungry fish looking for a snack.
Any number of hydroponic rooting media, such as peat moss, sawdust, wood chips, chipped bark, sand, gravel and crushed rock, gardener's heat-expanded mineral soil conditioners (such as perlite and vermiculite mixed with sand), expanded clay pellets
and other chemically stable media are used with varying degrees of success.