I've done photo and auto runs with the M3 its great stuff. Made itnalmost completely thru an auto run on only RO water, gave very lil bloom nutes at the end.
Hope the company is more on the ball now about a year ago I tried calling 3 times left messages, and never heard from anyone had at start calling random grow shops to track down some soil to test out.
I'd be using it now if it wasn't so hard to get. Promix bx is ok buts its not M3 thats for sure.