Cryptocoryne leaf drop

The abscission of Cryptocoryne leaves that Ken McNeil describes sounds a
lot different than the crypt meltdown.   I have seen the abscission only
once, and it wasnt serious, just a few of the oldest leaves that broke off
and floated on the surface.  Meltdown is another matter where the leaves
and petioles turn to mush.  Sometimes the petioles wait a few days longer
than the leaves, but eventually they turn to mush, also.

I have seen meltdown occur reliably when I add nutrients to some very
deficient crypts.  The deficiency is nitrogen for sure, and possibly other
nutrients.  My crypts have always recovered when meltdown occurred under
these conditions, and they don't melt down any more if I add more
nutreints.  It would seem that if the crypts are not deficient, then the
addition of nutrients does not cause meltdown.  I have also seen pretty bad
meltdown when I started adding CO2 to a 29 gallon tank where I had quite
low light, a single 20 watt fluorescent that was about to expire from old
age.  The high CO2-low light regimen did not agree with my crypts.  I
stopped adding the CO2, let them recover, and then switched to three 20
watt fluorescents.  With the much brighter light, I tried adding CO2 again,
and this time I had a very mild melt down of some of the older leaves, but
the plants quickly began producing much larger leaves and the meltdown soon
was over.  With the high light-high CO2 regimen, the Crypts soon filled the
tank up.

I don't believe that my experiences with meltdown have been caused by any
viruses or other pathogenn because the crypts recovered so quickly and
stayed healthy.

Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174
In sunny, soon-to-be-hot Mississippi