Amnesia Haze

Organic soil made of: Biochar, Worm castings, Alfalfa meal, Organic Seaweed, Azomite, Rock phosphate, Greensand, Neenseed meal, Oyster shell, Humic Extracts, Sphagnum peat moss, Perlite and Microbe Catalyst. Soil original PH: 6.0 - 6.5pH. Runoff PH: 7.2 I Have a White Widow and this Amnesia Haze growing on this soil. The WW is doing very good, in fact she is the most vigorous plant with the biggest buds I ever saw in a plant that is only flowering for 4 weeks. Now this one... is dying. It looks light she is consuming herself trying to put some weight into those buds. When the Symptoms started (light green all around the edges of the leaves) she was at 500 ppm level so I mistankenly thought nutrient lockout and flused her... Further looking into it I discovered this might be the symptom of a Potassium deficiency, what you guys think? I always feed at 6.2-6.5 but can't get the runoff to come lower than 7.2 I have now fed a lighter than usual mix of 0-15-8 and 0-0-50 organic ammendments but these may take a little time to work.