I have read all of the post too, and I know the good ole' cliche that it only grows in 'dirty' water. Well, my params are dead on and I have it thriving. I started out with one head, now there must be 30. I can't answer the what's and why's, but I don't buy into the 'dirty water' common excuse. My lfs can't keep it either, and I can guarantee you that their water is dirty.
For starters, don't put in direct flow. Start it off to the side, with some slight water flow. Next, don't directly feed it, but when you do feed the tank, don't turn off the ph's, so that some food floats it's way before all the fish get it. Next, put it mid-tank (light wise). They seem to spread upward as if they are reaching for more light. But don't start it out near the top, or your starter piece may get fried and never spred. Finally, bump plenty of extra rocks up against it. As soon as you see a new piece move to the new rock, move it to a totally new spot.