what is 'pg'? OH! per gallon. Are you using the general hydroponics stuff? You really gotta be more specific, I'll try to answer but I can't read minds.
1.23 mL/gal superthrive is WAY too mcuh. Dosage is 1 DROP per gallon. You get about 40 drops in 1 mL.

Drip system- what is your flow rate and how is it delivered? Emitters? Bare hose? Drip stakes? Other? Flow rate question is basically, is it DRIPPING or STREAMING.
Those blotches on the lower leaves are consistent with nute solution splashing constantly on the low leaves and leaching nutes out of them in a splotchy fashion.