Crypt rot

What excellent timing, Shaji.  And thanks for putting the effort into
this new list!

I have a bunch of Cryptocoryne sp. (probably wendtii or lutea) in my 45
gallon heavily planted aquaria (see, for instance, 
http://marge.phys.washington.edu/fish/Plants/People/Olson/ for full
desctiption).  The tank has heating cables, CO2, and 160 watts of fluorescent
lighting.  Starting about 2-3 weeks ago, virtually ALL of the brown "wendtii"
began to melt; I went on vacation and now that I'm back it's completely gone
except for a few newer shoots.  More of the green "lutea" seems to have 
survived, planted in the same area & mixed with the brown "wendii".

Here are some things I have changed to the tank that might have brought 
this on:

  * Removed a lot of pygmy chain swords and replaced them with 3 species of
Anubias about a month ago.

  * Uprooted lizard's tail (Saururus).

  * Added 2 or 3 rhizomes of Crypt pondetifolia (sp?) in another part of the

  * Added several bunches of Ammania sp.

  * Added an Echinodorus osiris (which was doing well initially but has
    seemingly stopped now).

  * Lowered tank temperature 80-75 F approx. TWO months ago.

What has NOT changed much is nitrate level, which I've checked weekly.  I 
also do regular water changes of 4-8 gallons per week or two.

So... I would like to learn more about Crypt rot.  Is this a seasonal 
thing, perhaps triggered by changes in our water?  Is it a reaction to 
other plants?  Given my situation, I don't think it's due to a change in 
macronutrient level (which most of the books suggest) as that's been pretty 
constant.  I have noticed in the past that SOME of the crop will die out 
and come back, but I've never had such a mass suicide as this.

     - Erik

Erik D. Olson                		The Job-o-meter:
olson at phys_washington.edu             	stand by...