I would like to consult the expertise of anybody here who has kept neoregelias with success in a vivarium - what are the requirements and pitfalls; and what am I doing wrong with mine?

I have tried a number of neos in my 20 gallon, and none of them have done very well. They all eventually develop some sort of rot or condition that wilts the leaves and turns them yellow/brown. I've experimented with a number of different methods of keeping them. Some I planted in the substrate; some I glued to a piece of cork/driftwood as epiphytes.

I used to keep water in the center cup of the plant, but after they started wilting, I generally try to keep the cup clean except for the occasional misting. I know overwatering causes rot so I water only once a week. The soil in is kept moist but not wet. The wood-mounted specimens shouldn't have any problems with overwatering at all and yet they shrivel up and turn yellow, too. I don't know where I'm going wrong.

Some details:

Light is provided by two 15-watt fluorescents, on for 10 hours a day.

I mist once a day, sometimes every 2 days.

Substrate is ABG mix, a combo of bark, charcoal, peat and sphagnum moss.

The humidity of tank is kept about 50 - 60%.

Temperature hovers between 75 and 85 degrees F.