i have a question reguarding flood and drain/ ebb and flo systems.... why are some systems simply flood tables with a medium such as hydroton clay pebbles filling the table and others are flood tables with square pots filled with hydroton. In other words some F&D systems use containers/pots, and some dont. what exactly is the difference, advantages, purpose? what do the pots do? do they simply keep the roots from neighboring plants being tangled and competing or is there another purpose?