A few questions..

How long has it been in the 3 gallon pot?

The PH you listed. Is that the PH of the solution you mixed or of the runoff that comes out the bottom of the pot?

Your source water PH is extremely high.. 8? What is the ppm of your water, is it well water or city water?

How many gallons did you flush with? for a 3 gallon pot you need 9 gallons minimum; also you flushed at the wrong PH. You wanted to flush between 6.3 and 6.8. 7.0 is a bad ph for soil.. or really for growing cannabis in any medium.