Kratkey fail

[HiPoha]

I have a tray filled with 25 gallons of water and decided to try the Kratky method of growing lettuce and assorted greens. I mixed in 60grams MasterBlend, 30grams calcinit, and 30grams MagSulfate. My results in growing anything has been very poor. Lettuce refuse to grow, bok choy are having a hard time , and so is everything else I put in there. What am I doing wrong? The grodan medium are sitting about 1/4 down in the water so the plants are getting what it needs. My previous nutrient solution did a lot better than this, maybe I should go back to that (CNS17).