I have been told with some authority that the limiting factor in Aquaponics is Potassium (K).  What this means is that when plants grow, they remove all the K, and can't use the other nutrients.  This means that Nitrogen  builds up.  This is what I measure when I do the Nitrate test.   This suggests an approach for determinng the amount of K that needs to be added to zero the Nitrate level.  Sinc…