After mixing in the nutrients you pH. You're growing organically it takes time for the microbes to break down the organics to feed your plants. The yellowing of the leaves are the plants taking the nitrogen from the leaves because there is not enough in the root zone. When growing organically you want to feed the soil before you ever see nutrient deficiencies in the leaves. I would also not pH down to 6 in soil. Would keep it at 6.4-6.8 range.