My local hydro store had these. And they are supposed to be devoid of any nutrients. He had sold me on it. And I didn't even realize it was a 45$ bag until I got home. Question is the FLX can come with additional stuff if requested. If something is added is there a way to tell. Do they label the bags differently mark them in anyway. It just says on the back undern ingredients "custom blends available " is this promx flx any good. Or did he up sell me..Also If im adding beni bacteria and micro and macro and calmag and advanced nutrients connoisseur .. will that be enough?