Nate Storey has done it again!
Figuring out nutrient imbalance is in my opinion the most difficult thing about aquaponics. Nate really lays it out in an easy to understand method for us to determine a course of action when our plants begin to look a bit peeked. I would post the link to the KEY he has developed for diagnosing these problems right here, but I feel that you should go to Nate's site and find his offer. When asked to register just do it. You will be pleasantly surprised.
Videos by Nate's