a UVB Bulb question

[Hustler]

Ok,
I have a fair ammount of understanding when it comes to lights, flourecents as well.....
But UVB bulbs.... i dunno
with hydroponics you re create the sun as best you can using 5000k and 6500k flourecents or a step up is metal hilides or high pressure sodiums...
All of these bulbs that are commonly used with amazing effects are dirt cheap lol
Are they producing UVB as well? or is this a magic pixi dust that only the pet store bulbs have on them and thus 3-5 times the price?
I will assume this is alot more technical then that.... But every time I buy something I find out there is a "hardware/grocerie store" equivilant thats half the price and lasts way longer then the suggested $55 reptisun that needs to be replaced every 3 months to be activly producing UVB.

 

[SnakeyeZ]

I hear ya... and if you find anything let me know. I am using MegaRays and at $55 CDN it add's up quick.

 

[Yvonne G]

I suggest sending a PM to Balboa. Seems like I remember he's an electrician and has a good knowledge of this subject.

 

[Madkins007]

Here is the spectrum emitted by a Metal Halide- http://en.wikipedia.org/wiki/File:Metal_Halide_Lamp_Spectrum.jpg. You should notice that there is almost NO emission above 350 nanometers, and the key wavelength that converts UVB to vitamin D is 280nm.

As far as the fluorescents- the older, 'fatter' T8 bulbs do emit some useful UVB, especially the 'superwhite' high temp versions. In general, you need 4 each of the 48" or longer bulbs to come close to offering enough UVB.

Lighting for plant systems do not need to emulate the entire color spectrum- in fact, they usually focus on the blues and reds- the colors most plants use. The eyes of tortoises need a more balanced spectrum for optimal health.


Actually- LOTS of bulbs produce UVB- but most bulbs are coated in such a way that most of it is converted to usable light. After all, constantly being bathed in UV lighting indoors would damage our skin, eyes, fabrics, plastics, etc. Pet and specialty bulbs get a specialized coating to allow more UVB through. Because this is a LOT less popular, it costs a chunk more.