[razorfingerz]

if i ran 2x 250w 14k bulbs over a 55g tank would i need actinic lighting.. or could i just use 20k bulbs.. would i need actinic lights then?

[Ninong]

Most 14,000K and 20,000K metal halide lamps are quite blue all by themselves.

[Reefland]

It is also dependant on the brand of bulbs you run. The Phoenix 14k are more blue than a lot of the 20k's I have ran, for example. The kelvin rating most manufactures use are for marketing purposes more than to describe the true coloration. I just recently got some Icecap 20k's and they would be better described as a 14k compared to other bulbs.

[Ninong]

Yes, there is a tremendous variation in coloration between brands and even within the same brand between different wattages. Some 14,000K metal halide lamps are bluer than the Radium 400w 20,000K lamps and the Radium 250w 20,000K lamps are bluer than the Radium 400w 20,000K lamps. By the way, Radium does not call their lamps 20,000K, they just call them blau (blue). And the Iwasaki 150w 50,000K medium base metal halide lamp is not nearly as blue as any of the 14,000K and 20,000K lamps on the market.

To add to the confusion, identical lamps can differ in appearance depending on the ballast that is used to run them.