Well if your plant is yellowing it usually means its a Nitrogen Diffenciency. Not Nute Lock up, this looks alot worse. Like ur plants twisting, dead spot over them, drying up. So flushing might not be the solution, just given it nutrients that is high with N could fix the problem. I Also agree with Tellno1 no matter what u have to PH Test your water, u never want to risk it. Flushing would help nute lock up if caught early but since its yellowing and u flushed it it might progrees deeper into nitrogen Diffenciency which can be a huge problem.