Java Fern rotting

Hi.  Had an interesting problem develop in the last 2 weeks I'm curious 
if anyone's also seen.  I have a huge growth of Java Fern (four 
different varieties, including two grown from Karen's cuttings) on a 
piece of bogwood in my 45 gallon semi-high tech tank.  In the last week, 
I've noticed a lot of the leaves have rapidly rotted away, first 
developing brown spots which eventually spread to the whole frond.  Here 
is what has changed in my tank recently:

  1. almost 3 weeks ago, I pulled the whole piece of bogwood out of the 
tank for about 30 minutes to an hour, where I pulled off about 1/3 of 
plants for auction.  During the hour, the bogwood sat in an empty tub, 
ie, open air.

  2. one week ago, I  re-adjusted my CO2 reactor such that it has become 
far more efficient (see posting earlier in the week).  The pH got down to 
the very low 6's for probably five days before I got to it yesterday & 
started adding carbonates back to the water (it's now a respectable 
6.8-7.0 again).

  3. I've been pretty lax in my fertilization the last month or two as well 
(durn this job thing), so nutrient deficiency theories are welcome.

Any ideas?  It looked like it was "spreading" to newer plants later in 
the week, which is worrying me greatly.  No other plants in the tank seem 
affected (aside from the Crypts, which melted after I changed the water 3 
weeks ago; I've grown to expect this).

    - Erik

PS: rec.aquaria.freshwater.plants -- Yay!

Erik D. Olson					         amazingly, at home
eriko at wrq_com