:O put what you have in buddhas tank...
might be the water :/ I dot think duckweed likes clean water.
if it does die let me know and I'll ship you some more for free when mine multiplies out again.
I didnt know you can kill the stuff... I accodentally buried some and one is up against the tranparent wall in the container under the soil. its been three weeks and its still green...lemme take photo
edit: added photo
can you take a photo...? It might actually be the salvinia that died..