Sorry, but I'd have to say you have pretty much a zero chance of getting oncidiums and dendrobiums bloom under 2 40 watt bulbs. I've been able to do it using 4 40 watt bulbs and I think that would prob. be the very minimum.

so only my paph and phals would do dencently ?

Can you add more lights along side the one you have?

The best solution is to look into getting T5 lights from a hydroponic supplier. I've bloomed just about all species with T5's

With all lights, cutting the distance between the plant and light source in half doubles the light. But with Dendrobiums being so tall, it is very hard to get the lights closer when hung over the top of them. You can mount the lights vertically as well, but probably only if the plants are growing in a basement since it doesn't lend itself to showing the plants with all the glare in your face.

i just dug up an old 10 gallon aquarium with a mesh hood on it.i was wondering how a waterfall would contribute to air circulation.i have an extra pc fan but dont know how to get it to work on regular power.i have some tillandsias that will prolly go in there with a paph insigne and some smaller phals. i have an epiflorum floribundum that i dont know what to do with so it might board up with the others..oh aobut the t5 what sizes do they come in?i have a hydroponics shop in the next town so i might go check it out.maybe theyll have somethin for ventilation.any tips on orchidariums would b great

I use the old style twin-tube 40W shop lights in a very dark corner of the greenhouse which gets almost no outside light. I bloom mini-catts, Sophronitis cernua, some rupicolous Laelias, smaller seedlings of several other strong-light growers, as well as Phals and some Paphs (I don't do Oncids). The plants mentioned have no problems growing and blooming. But the higher-light ones have their leaves just about touching the tubes, the lower light plants are about 4" below the tubes. Been doing this for years.

Holy Heck! A 40 Watt Fluorescent bulb?

I didn't know the numbers, so I did some research. A 40 Watt Fluorescent bulb emits the same light output as a 200 Watt (depending on the brand) Incandescent bulb.

I use a 15 Watt CFL, which I'm looking to up a bit, but my Phals and Oncidiums and Epi's are performing beautifully.

Here is a link that might be useful: Light

I am talking about a pair of 4' long 40W tubes which have been used for decades on plant light shelves. I am not talking about 40W CFL bulbs. Right under the tubes, my light meter gets buried over 5000fc (it only registers up to 5000fc even in direct sun). It's apparently enough to bloom most orchids depending on their size and placement.

Flourescent bulbs - regardless of whether they are CFLs or tubes will emit the same light output that I mentioned above. I didn't say they weren't enough. I said they were more than enough.

Mike, since both fluorescent bulbs and tubes loose their intensity rapidly as you move even a few inches away from them, it is very difficult to grow tall plants under them efficienty since the lower leaves are in a very low light situation. Plants growing underlights should be able to have most of their greenery up close to the bulb or tube. I don't grow anything under the tubes which is more than about 8" tall for that reason. Wattage means less than footcandles when placing your plants, so use a light meter to measure the footcandles where the leaves of the plants are.

I used to use a grow tube and a bright white in each fixture. I finally switched over to bright white only and the orchids seem to do just as well.

I also keep a couple angled old door mirrors horizontally behind the shelves hoping to reflect back some of the light onto the plants. As for whether they've helped or not, I don't know; I had them so figured I'd use them rather than toss them in the trash.

I had my calculations messed up in my previous post. You might assume that if you move an orchid so it is twice as far away from your light source that the light would be half as bright. In reality, the light is one quarter as bright. At one foot from a lamp which outputs 20,000 foot candles, the light level is 2000 foot candles. At two feet from the lamp, it is 500 foot candles. If you use a mirror, you are getting some benefit, but the total distance from bulb to the mirror and then to the plant reduces the effectiveness.