Well i let smart people go with verdicts shovel is a wise man from what i have read, and shovel thanks for the advice about letting nature take its walk
Anyways i have not heard about a flush hurting plants unless you do it too often. But i would suggest thinking about what shovel said maybe try and ask stinkyaddict? and then do ph meassure on the runoff and from a flush, i personaly flush my plants bi-weekly and have yet to see any problems with it.
Again i must enforce that you ask the wisest people you can find