Thanks Teresa, that's good to know. I started only turning on 1 set of lights for a shorter photoperiod. There hasn't been any more die off, and what's left looks really good. Not sure if it's directly because of the reduced light, or if everything has settled in to the new arrangement and stabilized. It makes sense though that if there aren't enough nutrients in the water to be utilized by the plant, that having too much energy from the light, wouldn't work. Haha, I've never quite faced the trouble of having too clean of water before!