As far as I know, if you are not using a flush agent (final phase or something similar), you should use 1/4 strength nutrients to flush your medium (soil). Too often is a matter of not drowning the plants or creating root rot. You should flush with diluted nutrients the first time, 5x the container volume, example, you have a 1 gal. container, flush with 5 gal. of weak nutes. After that follow up with pure water for the next 10 or so days. Don't be afraid to let your soil dry in between, depending on your soils drainage will control the frequency you flush. Good Luck!
