All along your grow, except for that *bloom booster* you used about 3 times, you have an organic grow my friend. This means you don't have to flush, if by flushing you mean rinsing your Promix with gallon of water with plenty of runoff, and or doing this with a *flushing agent product*. You should not do this at all.
All the good living organism you've busted your ass (and spend top $) to put all along your grow should stay in your Promix and will help terpene and resin production. All you need to do by now is giving fresh water tiil the end and avoid runoff.
Awesome looking plants, looking delicious and frosty like we Love! Cheers from montreal!