plant leaves dying other plants healthy....

My tomato plant leaves are drying up and dying. The other plants under same conditions (snap peas and jalapeno) are d oing well. Conditions: ebb n flo plants in 4x4 cubes(problems started when transplanted to cubes) fed flora nova @600ppm every 1-2 days. Tap water at 300ppm. Under 400w mh air cooled 75f 45%Rh Ph 6.0 and rises considerably ~to 7.00 after each feeding. Thanks everyone for ANY advice.

I would greatly appreciate any thoughts. I have done much research but am still at a loss.

looks like a fungus - could be in the roots which would prevent the foliage from getting sufficient water - good luck