Couple of Thoughts...

On your PH... 5.3 is way to low for soil IMHO, 6.3 is more in line...

That Schlutz Nute is off the chart in "P" so your low PH is probably locking it out...

On Flush... Might try something like Botanicare Clearex, works wonders...

Clearex | Botanicare
ZZTops Reviewed by ZZTops on . Leaves turning brown, drying and dying. What is your experience level? (first timer, novice, experienced...) Smart N00B :D Your Equipment: .1) Type and wattage of lights. (MH, HPS, CFL's, tube fluorescents, LED's) T8 Fluoro 4x32w, 4x60w CFL - All @ 2700K .2) Distance from tops? 3 inches/scrog Rating: 5