Since we are using volcanic stones and hydro granules as a growing medium in our system, mud, silt and fine gravel gathers over time on the bottom of the growbed. This could become a substantial problem for the water drainage, once it becomes clogged up with all the material. Aeration for the roots also declines. Therefore it is necessary to clean the whole growbed; first we laborously removed the volcanic stones to rinse them. Then we had to move the plants to antoher growbed temporarily. After all stones and plants were moved, the growbed container was given a thorough clean up. The last step consists of replanting the plants in the freshly prepared growbed. For two people this operation took two whole days.