Can someone help me here!? to determine from the photo what is with the plants!

I cycle my pH between 6.2-6.6 over the grow, but never go lower as I have had nutrient locks when it's too high or low. Could be a mag deficiency as the tips of the leaves are brown and yellow on the lower leaves. That is fairly common and easy to fix with cal-mag, but you probably know that already. I saw another comment about your roots which is spot on they don't look healthy. I got out of growing in hydro, because it moves too fast and I am forgetful, but I continue to use a mycorrhizae additive like white shark or recharge for healthy roots. All the best with your grow, Bud! Success!

Yes, somthing important is missing here. I assume there is plenty of light and nutrients already in the water. I think there are no bad bacteria in there, because the water is airated very good. In my opinion calcium, magnesium and maybe zinc is missing. This plant is fighting for its life. maybe it is already too late, but you may try to rescue it. FraFra

Your roots look pretty anemic to me considering their length. They should be branching out a lot more than they are. Pretty sure you got root rot or some type of bacteria that's attacking your root system. You can try adding a little peroxide to your solution....like 5ml per gal. That could help.

cal-mag?