You are drowning them. RW holds water like a mofo and has to be able to dry out some or the first to go will prob be from stem rot. Try cutting it back to like 10 mins every hour or two. To start your water level should be right at the bottom of the basket so the spray from bubbles can wet the hydrotron. Try and keep water level up as much as you can to keep the "splash" effect effective. As for nutes you dont stop nutes until you reach a week before harvest to do your flush. Nutes get mixed and added to rez and the plants feed directly out of rez.