Hey, have you considered raising your Ca? I heard that might do it
I had similar problems last year Brad and did end up swapping out most of the LR as you've alluded to. I noticed a burst of growth but then it dwindled down again. I later dropped my flow rate and found that lead to a burst of growth but wasn't sustained either. I've since moved and am dealing with typical "new tank" type symptoms including browning out and slowed growth.
Have you considered changing to LED lighting? I think that's what the cool kids are using these days. Sounds trendy and trendy is always good