And the way it works is that there's a pump at the bottom, which periodically sends this liquid nutrient solution up to the top, which then trickles down through plants' root systems that are suspended in clay pellets -- so there's no dirt involved.
E funciona cunha bomba no fondo que envía regularmente un pouco da solución nutritiva líquida á parte superior, que despois cae gota a gota por entre a raigame das plantas que están colgadas en boliñas de arxila, de modo que non hay suciedade.