it`s a good idea to change nute solution every week or 2, and flushing is not only for, just before harvest, if you put too much ferts in the solution, it`s a good idea to flush it out with plain water.
but yes, flushing of the plant is usually during the last few weeks of flowering stage.
and remember, when adding water to resevoir between changes, only add ph balanced water, not nutes mixed in.
hope this helps
notanovice Reviewed by notanovice on . Flushing Bubbler Hrdro System I have a hydro bubbler system you don't have to flush the system do you. I have not done that since I started 5 weeks ago and plants growing inch or more a day. I thought since the roots are sitting in water you did not have to flush them or do I not know what your guys are talking about. Is flushing changing the water if that called flushing I have done that one since start. I thought flushing them meant to flush them from top down and I didn't think that you had to do that since the roots at Rating: 5