How long have you had the crypts in there?
Sometimes when they're put into tanks they go through a dying back period, as most are grown out of water, and the new shoots have to adapt to this. If they have been in a good few months, a weekly fertiliser may improve the growth rate and leaf health.
The java/windelov (as i think it is) will brown off just before producing new shoots.
Hope this helps
Skittles