All High Kelvin temp Bulbs typically have Peaks in the UV
range. That is one of the reasons that they are so popular for reef systems. The exact reasons that were indicated in the NG mag.
In fact you can convert the temperature of the bulb in kelvins to the peak energy in wavelengths using this simple formula:
Wavelength = 2,900,000 nanometers / T (in Kelvin)
for a 10,000K bulb = 2,900,000 / 10,000 = 290 nm
for a 20,000K bulb = 2,900,000 / 20,000 = 145 nm
our visable light ranges from 700nm to 400nm
anything greater than 700nm is infared and anything smaller then 400nm is ultra violet. So clearly 290 and 145 have peak energy in the UV
Funny thing about this is that these bulbs are giving not only an owner's fish a nice tan but probably the owner as well
I call a 20000K bulb in an aquarium Fish-fry
As aquarist, I think we have to be careful as there is a fine balance that we must strike, in all fairnesss to the creatures we keep in captivity, between the beauty they provide us with, and the health they more than deserve. I'm not so sure that bathing these reluctant guests with huge amounts of UV
to make them glow is particularly fair. It may actually be a little selfish on our part. It seems more our duty to provide them with the exact or closest conditions to their natural habitat that we can. Just an opinion, please don't jump all over this - it is a very individual choice.