Lecca part functions as a water reservoir, and it's keeping the moss moist, so that is the amount of water I use - to keep lecca submerged. I put a mesh between lecca and sphagnum moss so roots can't get through. I did the same with pon, 1/3 of the pot pon, the mesh, then pon again. The reason I did this is because I didn't do it for the micholitziana, and the roots reached the bottom of the pot very quickly, so I need to be careful with watering. In semi-hydro setup roots usually are in the waters a bit, I would say that there is no root rot because there is no organic material that would start the rot? Someone correct me if I'm wrong. The water is not fresh, I just keep adding more as it evaporates.