I'm definitely going with tank raised, so hopefully that will help with the disease risk.
I'm going to have to wait at least a little while now. The nem has been hanging upside down in a cave since about 2 days after I got it. It squeezes out between a couple of rocks during the day to get light. In my infinite wisdom, I decided to move one of the rocks. Now the nem is just hanging in the cave and won't come out at all...Hopefully, this doesn't mean a 'wander' is in it's future. I want to make certain it's comfortable and happy before adding any clowns.