Lighting - Lux and Kelvins...

[stevelikesfish]

Ive just bought a couple of Power-Glo tubes for my 50G tank.

They are rated at:

30Watts
135 Lux
18,000 K (Kelvin)

The tube packaging says that they promote invert and coral growth blah blah blah, but I was under the impression I would need something like Metal Halide to do that...

Basically, what Im asking is, is it more Lux the better? Same with Kelvins ?

Thanks all...

 

[fishfreek]

Kelvin is the measure of at what tempature a black body mass would radiate the color of the bulb. For example the above bulb outputs the same temp as a black body heated to 18,000 kelvin. The higher the kelvin the more blue is in the bulb. In addition the lower the kelvin the more yellow, reds will be in the light specitrum.

Par is the light output that many lighting studies have used. Lux is basicly the measure of candle light. 1 lux is the intensity of 1 burning candle flame at something like 1' distance. So 135 lux is equivlent to 135 burning candles.

TO be quite honest the bulbs you have are normal output and I wouldnt use them for a reef tank unless the tank was very small. You should shoot for something like 200W or more over your tank.

 

[stevelikesfish]

ok, thanks for that info... So when buying bulbs, am I looking for as much lux as possible and as much K rating as possible, or do I go for a mixture of K ratings to get the different color spectrums?

Thanks again!

 

[fishfreek]

Overall a NO florecent isnt going to have much difference in LUX. Another important factor is LUX only measures the visable specitrum. With this measurement an actinic bulb has a very low lux rating while a good bit of the specitrum that is output is out of the human visiable range.