chances are, if you have deficiencies its the fault of your whacked ph, and the plant not uptaking because of it.
ph your feeding, ph your water??? of course
"flushing" plain water doesnt rid the plant of excess nutrients, but it certainly pisses your plant off, kills beneficials, and reduces oxygen in your root zone. I'd just begin ph'ing and feeding properly, without "pushing" anything.
In all my years growing the only issues I've ever had was when I didnt follow the directions on the bottles.