Mark,

Not sure how 'pretty' you are wanting, but here is a link to a site that has some 'pretty' options at reasonable prices, a 36 (dual?) watt unit may fit nicely. The bulbs can be bought at other places, just Google CFL and the wattage you need.

I used a dual 55 watt set-up I purchased from the AH Supply 3 years ago over a 20 gal high tank (retired the small tank, using light for other areas now), I use another dual 65 watt setup I received as a gift from my wife over a 55gal set-up. I can't remember where she purchased that unit, but it is a really nice self-contained unit made for aquariums. I get my replacement bulbs the least expensive places I can find on the web, as I've never seen these types of bulbs in the any of the big box stores.

If 'pretty' isn't important, take a look at some of the 40-65 watt spiral CFl's, as they are a lot less expensive. I generally can only find up to the 42-43 watt varieties in the big box stores on these also.

HTH,

Bob

Here is a link that might be useful: AH Supply

"I want to cultivate require from 500 to 2500 foot candles"

In an 18" space? Wide range of light requirements. Not sure you can accomplish that in an 18" space. Why not pick a couple on the lower end to start? Not sure what orchids will flourish at 500fc's. Even Plueros I.E. Dracs require more fc's. Then heat becomes a consideration. Bear in mind that light requirements for orchids are usually given in minimums

cfls kick concentrated heat. How you planning on keeping the temps from frying the plants? Example: A 120W cfl (actual wattage 30W) will give you 2000 lumens and boat load of heat. Not sure if the response above is referring to actual wattage or "like" wattage. Assuming the poster meant "like " wattage 30-45W won't be nearly enough for intermediate growers. You may want to look in the direction of tubes and go with low light orchids. Good Luck
Mike

Thanks for the reply. I know that an 18 inch set-up isn't much. As for the heat issue I have an ultra-sonic fogger that should keep things cool, in addition to an internal fan and an external that should provide the air circulation. We'll see what happens.

"I'll go bigger once I know what I am doing". Flawed logic. A larger system is better for experimenting because mistakes are not instantly catastrophic. I don't think a 30W CFL throws a 'boatload' of heat but it does of course emit heat and easily enough to raise the temp of a small chamber to deadly levels should a fan fail. A fogger does nothing to cool the air unless the source water is itself chilled. You should also know that people growing in orchidariums do not attempt to supply anywhere close to natural light levels inside. A decent rule of thumb would be to aim for half the natural level (natural average usually ~4000fc) for twice as much time as a normal day (~8hr). Only a few orchid families need light above 4000fc: standard cymbidium, cattleya, vandaceous type and some other things. The rest do fine with ~3000 more or less. If you can supply half that (1200fc - 1500fc) for 14 - 16 hours you can do well under lights. Doing so is not as easy as you think with tubes. CFL are almost the only way. The 36 and 55 watt CFL are aquarium lights and have four pin bases and they and their fixtures are not cheap. Spiral CFL are household lamps and have mogul (screw in) bases and are heavily discounted. Can you tell which kind I recommend? You will not be able to generate 2500fc, nor do you need to since any orchid that needs natural intensity of that range would be too big for an 18" case anyway. For the mini's that you would be limiting yourself to ~1000fc should work fine.

H

When it comes to light, listen to H.

I was actually referring to the actual CFL wattage, and yes there is some heat but a small computer fan(s) suffices nicely to help alleviate the problem.

My experience over the last 3 years of growing in tanks says that for me generally the tank stays 4-5 degrees higher than the room temperatures when using small fans and aquarium type CFL's. I also found that keeping a portion of the top of my tanks open releases some of that heat. My tanks never got/get any higher than 85 degrees as the rest of my orchid room gets to around 80 during the summer months. The heat is really only an issue for me in the summer months when opening a window doesn't help to release the grow room heat. With the lights off, the tanks quickly return to 'normal' room temperature.

Interestingly enough I have temp monitors in my tank and when I mist heavily with room temperature water the temp drops 10-15 degrees within minutes or even seconds. It won't stay there very long, but it does drop it significantly for at least 30 minutes.

As Howard mentioned, the aquarium style light set-ups are expensive, but I think the actual bulbs are not than much different in price from the same wattage spirals if you look around the web hard enough.

I generally have mini-vandaceous types in my tanks, I'm not sure any cool growers would make it through the summer heat.

YMMV,

Bob

well not sure if this will help or not but here's my set up...
I have a tank thats 48"x24"x24" and inside the hood I installedc 8 of the mogul type sockets. I run 6 of the 100 wt equivalents and 2 of the 150 wt Eq (42wt actual)
Inside the tank I grow Mini-catts, Tolumnias, Rodrigezias,(hanging near the top)and Phal-type dends( the shorter varieties) and a a couple of smallish phals( in the bottom of the tank). These are all warm growers so I don't worry too much about venting heat except in the heart of summer when the sun coming thrugh the window raises the temps to near 100. but with just the bulbs for light (away from the window) my summer highs get around 90. I've found that with just the light bulbs going the temps will climb about 15 deg above the room temp the tank sits in unless you vent it a lot and then you lose the humidity.
I'm thinking of putting in solid panes of glass just below the bulbs and then venting the heck out of the bulb space to see if it helps.
I'm not sure how well you'll do with cool growers but set up the tank and pick a couple of cheap cool growers and test em out before you buy the expensive ones.
Good luck!
Adam