I have a 4x2x2 terrarium that contains dracula orchids and heliamphoras.  The orchids are not doing as well as I'd like, and I have grown suspicion that this is due to not dropping the temp down to an appropriate 50 degrees at night.

Terrarium is totally automated, it needs to run for days at a time without my input, so ice and anything that I have to replace constantly is not an option.

You folks have ideas?

Greg,

    There was a fellow up in Cleveland some years ago who successfully grew cool orchids in a terrarium. If I remember right, he actually used refrigeration. His name was Frank something. Perhaps you can find someone in the West Shore or Greater Cleveland club who can put you on to him.

Greg.

I believe folks have used a cold water closed loop refrigeration type set up. Basement would be a good start.  You may wish to try warmth tolerant types but they are not so cool.  Dracula's are really cool plants but a really pain in the but to grow.  D. lotax might do better in that situation.  One of my friends grows Disa and he uses refrigerated water and flood trays.