Yea read up on that. Seems there's a lot of debate regarding the flush. It really depends on how well you've operated your system. If you haven't tried pushing the ppms, and are conservative about it, ie no nute burn or stunting due to problems, then you will be Fine running normal range ppm all the way to the finish. What I do is get lazy the last estimated couple weeks by checking trich and nOde growth, if alps good then just top Off res with just water. Try it.
