My guess would be that they aren't getting enough nutrients. I'm not familiar with leaf zone, but I doubt it has anywhere near the amount of NPK a plant needs when added once a week.
The lighting you listed seems strange to me. Are these 4x 18" bulbs? What kind of lighting are they, T5, T8?
The lighting you listed seems strange to me. Are these 4x 18" bulbs? What kind of lighting are they, T5, T8?