Re-read my last post for the amount to use. I stated in this thread several times. As far as using it the whole flower period, I don't know. When I called the company that makes Pysan, the lady on the phone said you could. I didn't want to try and find out. I think you will be the first if you do it. Let us know. Something tells me it will be ok. And, if it is this product will be the absolute best additive for a sterile resevoir. And its super cheap.