I put a new root tab under my melon sword a week or two ago and it's putting out all kinds of white roots and 2 new leaves, in the midst of a Cyanobacteria bloom. So I think they work, maybe take a week or two.
I don't know PAR values off the top of my head, but check out the thread on PAR posted by Hoppy and look at the tank in terms of brightness.
Every staggered light description I've read was 4 on, 4 off, 4 on. I don't know that that has anything to do with these problems. It sounds like perhaps one or more of the NPK nutrients is too low, or micros need to be at a higher dose. It has been difficult for me too figure out that kind of problem in my tank. Following is a visual of plant nutrient deficiency symptoms.
Nutrient Calculator: http://calc.petalphile.com/