I Need A little Zinc help

So from what I have looked up It looks as though I have a zinc problem. Some obvious fixes are lowering the PH, but I'm keeping it at 5.6 in my ebb & gro. The problem I'm having now is how to fix it? I could use some help.

Ok so we have the pH, now just need to know the ppm, air temperature at the plants top, how many times you are feeding a day (assuming its flood and drain), type of air circulation you are using, how many plants you are growing and on how many of them are showing this issue, strain, how old is the plant, how long since it started doing this, is it a seedling or a clone, what nutrients and additives you are feeding it, any h2o2 in the mix, and what are you treating your nutrient tank with in order to prevent pithium attacking the plants roots. Thanks.