Hi, Nick.
Compact, energy-saving so-called "full spectrum" bulbs (like the ones people buy for SAD, for example; the so-called "Daylight" lamps like the Sylvania Activa; and of course the ones sold as "Daylight" bulbs for reptiles, like the Reptisun 2.0 lamps) are not in the least hazardous to reptiles.
The glass they use, and the phosphors they use, don't emit any "bad" short-wavelength UVB. In fact, no UVB at all, in most cases, although they all emit a bit of UVA because of the mercury vapor "spikes" of radiation, especially the big one at 365nm.
Yes, some of them do also have quite nice visible-light spectra with a range across most of the colors in the spectrum.
But they are SO dim!
Compared to the sunlight, anything (except a good Daylight metal halide lamp) is dim.
But there's dim, and...well, very dim...
If you measure the visible light with a lux meter, typical readings are:
Sunlight (clear day - 21 June 06, here in UK): 5 mins after sunrise: 3,300 lux. 7.00am: 90,000 lux. 1pm: 164,100 lux
During rainstorm at 7pm the same day: 4,900 lux. 2 mins before sunset (sky clear again): 1,060 lux.
Here are some lamp readings:
480 lux : UVB fluorescent tube - new 5% UVB (ZooMed Reptisun 5.0) at 12”
1,600 lux: fluorescent compact lamp - new ExoTerra ReptiGlo 2.0 "full spectrum" daylight lamp at 12"
3,500 – 12,500 lux - various tungsten 60watt spot lamps at 12”
12,200 - 15,800 lux - mercury vapour: 100w ReptileUV MegaRay at 12”
49,000 - 143,000 lux – various 70watt metal halide lamps at 12”
Of course the most obvious reason for using an incandescent rather than an energy-saving lamp is that we actually want the heat. Because incandescents are dimmable, they are ideal for adding controllable heat and light to a merc vapour lamp.
I personally use some fluorescent tubes of the "Daylight" type for brightening up dark corners of a vivarium, I think they are great for lighting up the cool end without generating heat.
The reason I prefer the Daylight tubes to the Daylight compact lamps is more personal preference.... because compact lamps are such very large physical objects, and here in the UK, at least, people hang them down inside the vivarium from the roof, so they stick right out into the airspace, almost hanging down to the reptile's eye level in some cases. Have you ever sat with one in your line of sight? The glare is horrible. They don't light up the area very well at all, but they sure are nasty on the eye. Of course if they are in a dome, over a screen top, that solves the glare issue. There's no reason why you couldn't use one like that. Just get the brightest one you can find, with the best color rendering.
Hope that helps!
Frances
