Confusion about Light Intensity with 125W CPF

[bosco]

Hello All,

I've recently built an orchidarium (2'x2'x4' tall) and am illuminating my orchids with a 125W daylight spectrum CPF bulb. To my dismay, I measured the footcandle intensity only to find extremely low light levels even 2ft from the light (200 ftcandles detected with a light meter set to read fluorescent light intensity). I noticed that [some] websites suggest light levels of at least 500-1000 ft candles for shade loving plants like Gongora, and higher light levels (1500-2500 ft candles) for most dendrobium species... However other sites suggest lower light levels for most dendros (600ftcandles)

Of course one of the reasons for building this 4ft tall orchidarium was to fill it with orchids, however it now seems that I'm only be able to utilize the top 1ft of the tank. So I'm wondering, using a 125W CPF, what types of orchids can I grow that would be placed 3-4 ft from the light source? Why is there a large discrepancy of suggested illumination levels between different sites?

Thank you

Bosco

[smartie2000]

Phal hybrids are probably as low light as you can get.... and you would need to have the light on for long periods like 14-16hrs if the foot candles are really low. I'm not %100 sure if they will bloom down at 3-4ft

I suggest that you get several halogen bulb fixtures if you can. They also run on very little energy, but they get very hot. Orchids will have to be a distance away or they will burn them. I don't use them for orchids, but I have some lighting my family room and they look blindingly brighter than fluorescent ones. You can also use several bulbs, and place and focus them onto the different depths of the orchidarium. I just used my light meter to measure the everyday 40W ones and they are around 250-300 foot candles 2.5 feet away, but will be more with several bulbs.

[Diane]

You may want to consider using a fluorescent tube - running one down inside, along a seam or something.

[smartie2000]

Suggested fc vary from different sites because they differ from whether you are a green house grower or a fluorescent light grower.
Under lights orchids should get 300-800 foot candles depending on the species, which is less than the green house recomendations since they are getting that amount of light for a longer period. The suggested foot candle variations may also depend on how long the lights are on.
In a green house they are only getting the sunlight for a shorter period and the fc required are higher. BTW in the summer in the greenhouse, the fc requirements are lower because of longer day length
......fc suggestions all depends on the length of time there is illumination

[IdahoOrchid]

Check out these:

The lights are FluoreX Fluorescent Flood Light 65 watt by Lights of America.


I do not have any experience with them yet, but a club member says they work fantastico!!! They have two sizes even larger. The only thing is they are NOT plug and play and require just a little wiring to get them up and running.

[jrod]

By CPF, do you mean compact fluorescent? If so, 125W should be incredibly bright, almost impossible to look at. What kind of reflector are you using behind your light? The problem may be with your reflector or light meter, not your lights.

[jtlqh]

I have a cheap light meter, costed only $30. I found it very inaccurate. The better light meter would be your SLR camera, my orchid book has a section on how to use your camera to measure the light.

Qing

[smartie2000]

I was thought it would be incredibly bright too if it was a compact flourescent 125W. So what's going on?

[bosco]

Hi,

I have an agrosun 125W compact fluorescent bulb, with an equivalent rating of ~500W incandescent. Hydrofarm makes the reflector, at least thats what the logo on the side says. THe reflector material is a smooth brushed aluminum, and from my experience a very good material for reflecting light. The orchidarium is constructed of 3/8" thick cell cast acryclic with a light transmittance >95%. So I'm thinking the light meter is crap, I guess thats waht $30 buys. I'm borrowing a more professional light meter and will take some measurements this evening and post. Thanks everyone for the replies!!

[jrod]

Sounds like you've got a good start. If you're spending money for high light, and you're looking into high-light-transmission materials, you might want to swap out that reflector. Brushed aluminum is a decent reflector, but it's more of a diffuser, so your lights will look bright, but you'll be losing a lot of light out the sides of your orchidarium. If the "better" light meter is still reading low, and you'd like to try a different reflector, PM me. I'd love to post a vendor name here, because they're fantastic to deal with, but that's a no-no. I went through this same sort of trouble when I was choosing lights for my planted aquarium. Good luck!