coco -- fertilze every irrigation at 1.3-1.5 EC of well-balanced diet. buy "hydro" nutes that are 100% chelated and plant-ready. Get 10% runoff religiously each time you irrigate and it cann''t buildup in soil. you can feed too much, but you know it's not buildup when you see a tox symptom, which is a benefit. Easier to diagnose that you are giving too high of concentration of "something" when it happens vs guessing if it's a rootzone issue or formula issue.