Need help will this T5 Biax light work?

[mjsdas]

I'm very new to orchid growing and I'm in need of lighting help. In the near future I plan to purchase 3 or 4 Phapeopedlium orchids. I will be growing themon a 3' x 3' table which is located adjacent to a south facing window. I've already determined that there's not enough natural light available by using a light meter. Given my space constraints, I would like to know if a 24" T5 Biax Light would provide me with the necessary light to effectively growth the Phap orchids. I've attached an ebay listing which shows the light that I'm looking into.

T5 FLUORESCENT GROW LIGHT Compact 2' hydroponic TEK CFL - eBay (item 270197883283 end time Jan-05-08 21:15:00 PST)

Thanks for your help.

[Ocelaris]

Sure that will work fine, but may I reccomend a vendor whom I am familiar with and have used successfully (and they've been around for 10+ years now).

36 or 55 watt Bright Kits

What you are looking at is 2, 55w Compact Flourescents... basically it's two T5s stacked next to each other... T-5 is a catch phrase these days, and is technically I think only the double ended variety.



AH supply's dual 55w setup is 69.99 + (2x) $17.99 = 105.97 basically. Your ebay auction if you buy it now, 105$... Bout the same thing. I have the AH supply 2x36w kit and it works great. The reflector is better on the AH supply kit, much better with the multi-faceted design. At AHSupply you know that the bulbs that come with them are a certain color temperature (you should get the 5000k ones because they are 90+ CRI which is good for plants).

Now as for the amount of light, yes, those 55w will pour out a ton of light, paphs are not too demanding with light either, in fact they prefer less than more. It depends how high above the plants you put the lights too though.

I calculated that those lights are putting out about 10,000 lumens, at 90lumens per watt, I have the two 36w version, which is about 6500 lumens. I get roughly 800 foot candles at a distance of about ~10 inches above the plants. With those 55 watts, you might get upwards of 1000 foot candles at 1 foot distance from the plants. Which is IMO sufficient from my experience (as limited as that is).

Synopsis: yes those will work fine, just I would reccomend the AH Supply ones.

Hope this helps!

[Becca]

If you are looking at ebay to make a purchase, the seller of the following link has a much better feedback history and is about the same price and the product is more solid looking:

Compact T5 FLUORESCENT GROW LIGHT Fluorex 2 TEK 400 hps - eBay (item 180197999565 end time Jan-13-08 19:30:00 PST)

[quiltergal]

If you're only looking at growing paphs I think those lights are overkill. You really don't need that much for paphs. I'm growing one successfully under one 56W T5 with no reflector in a south window.

[mjsdas]

As I understand it, Phaps prefer lighting in the 10,000 to 15,000 Lux range. That is why I'm looking into the 2x55w T5 Biax light set up. It puts out around 10,000 lumens and this would allow me to have the light 12 to 16 inches above the orchids. It would also allow me to try other orchids down the round that require more light intensity. Although I'm a handy guy, I'd prefer to buy a light unit that is complete versus make one DIY. I definitely want to get a "quality" product. Thanks.

[Ocelaris]

There is an indirect relationship between Lux, Lumen, and Foot Candles. I just thought it pertinent to bring up how a theoretical "10,000 lumens" correlates to actual foot candles on the plants. Or do people measure in lux? I just got a light meter, and am playing around with it, but my actual light is much lower than I expected.

From Wiki:

Lux versus lumen

The difference between the lux and the lumen is that the lux takes into account the area over which the luminous flux is spread. 1000 lumens, concentrated into an area of one square metre, lights up that square metre with an illuminance of 1000 lux. The same 1000 lumens, spread out over ten square metres, produces a dimmer illuminance of only 100 lux.

Achieving an illuminance of 500 lux might be possible in a home kitchen with a single fluorescent light fixture with an output of 12000 lumens. To light a factory floor with dozens of times the area of the kitchen would require dozens of such fixtures. Thus, lighting a larger area to the same level of lux requires a greater number of lumens.

[edit] Lux versus footcandle

One footcandle ≈ 10.764 lux. The footcandle (or lumen per square foot) is a non-SI unit of illuminance. Like the BTU, it is obsolete but it is still in fairly common use in the United States, particularly in construction-related engineering and in building codes. Because lux and footcandles are different units of the same quantity, it is perfectly valid to convert footcandles to lux and vice versa.

The name "footcandle" conveys "the illuminance cast on a surface by a one-candela source one foot away." As natural as this sounds, this style of name is now frowned upon, because the dimensional formula for the unit is not foot · candela, but lumen/sq ft. Some sources do however note that the "lux" can be thought of as a "metre-candle" (i.e. the illuminance cast on a surface by a one-candela source one meter away). A source that is farther away provides less illumination than one that is close, so one lux is less illuminance than one footcandle. Since illuminance follows the inverse-square law, and since one foot = 0.3048 m, one lux = 0.30482 footcandle ≈ 1/10.764 footcandle.

In practical applications, as when measuring room illumination, it is very difficult to measure illuminance more accurately than ±10%, and for many purposes it is quite sufficient to think of one footcandle as about ten lux.