Hello Rafael, I am glad to can read to you here.
I think adding this nutrients to the crypts can be a dramatic change, so that can gets your crypts melted.
For the pictures i think you set up hasnīt a drainage. I deduce you have an accumulation of nutrientes on the bottom of this box. Am i rigth?
i have my crypts in perforated pots and with a low water flow... so i add the nutrients to the water. In my short experience a good dreinage is the way of the success.
i have watched sometimes crypt melting in my plants, overcoat when some change is done, After repotting plants or ligth change beacouse of the arrival of the spring of back to the winter, allways in this cases some leaves are melted.
Anyway... i post some pic i found about the Neil Jacobsen collection. It is when Rayon Vert people visited Copehagen in the ECS 2003 meeting.
see the dry-leaves in the soil...
Rafael, is your cultivation way something like this?
Another pics of a luxurius growth...
More pictures...
Greetings from Andalucia (Spain)