The issues that started around week 4 on the smaller plant have largely stabilized after raising the lights. I'm still seeing some deficiencies on both plants that I think are genuine deficiencies because the pH in / out hasn't been too worrying. pH going in has been around 6.5. Usually the runoff is around 5.5. I've been alternating between watering and feeding. My feedings haven't exceeded 1.6 EC. It seems the plants have just been hungry for food.