Now think about PH and how it affects the plants ability to take up nutes. If you can start at 6.3-6.4 and slowly increase the ph up to 6.8, during flower, you will see a difference in the plants. At 6.3, Nitrogen (N) and Potassium (K) and some micronutrients are readily available to the plants but Phosphorus (P) is not so readily taken up by the plants. At 6.8, Phosphorus (P) is readily taken up but some micros such as iron and manganese are not so available. It's a good balance for the whole cycle of the plant.
You need to be able to check the PH of the soil.
~PP~