Chris Schmelzer wrote:

Ideas? Lack of calcium has been a consideration as the water here is
pretty soft, but there should be plenty of PO4 and Nitrate as there are
a good number of fish in the tank---the substrate is very good Flourite,
what's the deal?!?!

Chris,

The answer appears to be in your paragraph above. Adequate PO4 and NO3 are
not a substitute for inadaquate Calcium or Magnesium. And you are guessing
about the PO4 and NO3 levels anyway!

Easy answer:
Add Kent RO Right to raise GH, and see what happens.

Cheaper answer:
Add Calcium Carbonate (Aragonite, crushed seashells, even eggshells) and
Epsom Salts and see what happens.

Likely outcome:
Plant growth will improve for a while, then you'll run out of Potassium
unless you have adequate supplies in your PMDD mix.

Good luck!