depending on the size of the case, one or two 42W CFLs could heat it up pretty well.

Should have stated that.

I'm thinking of using a 55 gal aquarium. The lights would be above this, so I'm not sure how much they would heat it. I've never used a 42 watt bulb on my other orchids, so this one would also be of lower wattage.

Some of that shiny thermal wrap that you can slip around the case at night? You could always stick a heating pad that automatically switches off in the sleeve and set it on a timer to turn on at 2-3 AM to provide a little extra heat.

I've had bad luck with aquarium heaters, but I guess, since you don't have to worry about electrocuting fish, it wouldn't be an issue to stick in a container of water over night.

Stacy

Stacy - Have you fried fish??

Here's an odd story. When I was a kid I had an aquarium. One day I was messing around with it and the hood with the lights fell into the water (the lights were on). Without thinking, I reached into the take to retrieve the hood. I have no idea why I'm still here today, but nothing happened. My Dad was an electrician, so I was very familiar with what could happen when you mix +/- with water.
K

Your problem is not heat but humidity. You have zero humidity (relatively speaking). Truth be known, these plants have a rather "static" temp range, then a lot of orchids. Say between 50 and 80. They can go lower and a little higher but 30 degrees (20 for most) isn't a huge difference. However, humidity ALWAYS needs to be high. This is why I can get away with growing them in Florida. Except for the summer, our temps are usually between 50 (night) and the high 70's (day) with high humidity at night year round. Yes, I've pushed them higher and lower but, truth be told, they prefer it between 50 and 80. Compare that to dends, catts, and laelia that thrive on swings between 30 and 100 and don't' mind drying out when it's cold. In your temps, you need to find plants that both like it cold and like it dry. Ask bada, he can tell you the horrors of trying what you are suggesting. L

Kevin. I grow in a terrarium and from my own expierience your lights will probably rase the temps about 10 degrees if you leave a little slit in the cover for air circulation. If thats not enough for you go to a pet store and pick up one of those reptile heating pads. They stick to the outside of the glass so they won't get wet. Just put it on the back glass not underneath because if water hits the glass while the pad is hot it'll grack the glass. I have warm to hot high light plants so I have a few more lights and run the heat pad during the day only to raise the temps. with this set up I get a 20 deg. temp diff from night to day
I also have a small fan in the tank that pulls air across the heated glass surface and circulates the heat

i have a 30 gallon terrarium set up right now. about an inch deep of pea pebbles on the bottom covered with water. humidity is around 90%+. i'm using one 42W CFL inside which generates quite a bit of heat.

Good suggestions. Thanks.

I also thought of another possibility -- a heating cable. I know I have a couple of these around here somewhere. They're flexible cables used in plant propagation and usually buried in the soil. I could also tape them to the glass.

I don't think I'm going to have a humidity issue. Since I have hot water heat, my humidity usually stays in the 50-60% range most of the winter. If I were to use the aquarium heater in the container of water, that would drive it up much farther inside the tank - heater warms water - water evaporates.

K

I've electrocuted fish and myself with the heaters. I'm surprised the lights didn't crack when they hit the water... I've done that, too.

I've given up tanked fish. I don't seem to do well mixing water, living things, and electrical parts.

Although I've never fried my fish, I did end up with some very expensive African style bouillabaisse.
Mom, dad and all the babies were cooked when the heater stuck!:~(
My systems are all now unheated and my fish don't need it!
With that exception, I had very few heater issues.
Although they can all fail, the big key is to buy the best and not cut any corners with something so vital.

Unless you're worried about penguins eating them, those winter temps don't seem that bad.
A large group of my Pleuro-types, that aren't in something else, spent a happy winter in an unheated backroom with little to no insulation.
My Dracs, Cold-loving Pleuro/Acronia crocodiliceps, viduata, etc and most of my Neos loved it and grew like crazy! :~)
The Neos were kept very bright and rather dry.
The others were in very large plastic tubs with a deep layer of clay pellets and water.
The humidity was kept up and they thrived.
During some of the very coldest nights, I either moved some out or pointed a fan into the room.
The house is wood heated, old and not exactly airtight.;~)
Between that and increasing the winter light, they did great!

I used heated seed propagation mats for a couple of years, until I started to heat the whole area.
They dramatically helped the roots from rotting in s/h.
That was the major thing for my s/h winter growing tropicals. Keep the roots warm!

Scott