nutrient def or over watering

All was going good, in 6' rockwoll. Was have leaf curl and thought it was from heat or over watering the cubes. They were heavy to the lift so i backed off on the watering to let them dry out. I water them by weight, if they are light I feed them. Feeding twice a day before all this happened. I backed off . Hitting them with 6 1000s, 5.9 ph, 750-800 ppm. temp over the canpoy is 80-88 w co2. My first grow with rockwoll

im no expert but it look like def to me.
What are you feeding it? How much? What are the NPK ratios?

Using SBA A&B 4-5 oz, hygrozyme 8 oz, cal mag 4, protek 4,