Have you tried dosing Potassium?
My Monti Caps were getting bleached and weren't growing and I read on the ZEO forum to try K-Balance.
I was on the full ZEO, but have switched to the Vertex Bio Pellets about 2 months ago.
Since then they have coloured up and are growing new ridges.
http://www.jlaquatics.com/product/zv...m+-+250ml.html
I only dose half the amount because I dose some other ZEO stuff.
It might not hurt to give it a try?