Question related to MH Color Temp.

[tirtha1979]

I am planning to setup a 4'x2'x2' tank with 2 250watt MH. Initially I was planning to use either 2 6500K MH or One 6500K and another 8000K MH. But I am bit worried about the Red Plants (As am not sure about the spectral distribution of those bulbs). Under 6500/8000 color temp will they do good or do I have to choose some other color Temp to keep them Red?

Please suggest.

P.S: I know ADA NA 8000K will be best option to go for, but it's not available in India easily also out of my pocket.

[CmLaracy]

Having two separate, different colored hqi's will not create a nice effect. One half will be a different color than another, and things will simply look different on the opposite sides. MH bulbs are not like fluorescents, as they are point source lighting. They affect a certain area, and then fade in strength rather quickly. Also, each lamp is assigned one general area, where fluorescents usually all light the same area, as they run the full length of the tank. Thus their colors can be mixed to create one definitive "color". The Metal halide light will not mix, and the parts of the tank under each different color light will look different. If you're using more than one MH fixture, aside from special cases, all the bulb colors should be the same.

I find that 8000K is by far the best color for MH's, not too white, not too yellow. It will provide you with all the red and green you need, as well as providing just enough blue to accentuate uniquely colored fish.

HTH

[tirtha1979]

Thanks a lot HTH. I was planning to use 1 6500K and a 8000K bulb, but now I will stick to 2 8000K 15watt Astralux.

[CmLaracy]

Originally Posted by tirtha1979

Thanks a lot HTH. I was planning to use 1 6500K and a 8000K bulb, but now I will stick to 2 8000K 15watt Astralux.

no problem man! And by the way, HTH mean "hop that helped" lol

Oh, and one more thing. Those Astralux's are known to be VERY green, even more so than the ADA ones. You may find that your reds don't pop as much with it... Some would actually recommend a 10000K over that astralux 8000K, but it may simply need time to burn into it's final color. If it ends up looking to green for your tastes, I'd try switching to some nice 10000K's.

[epicfish]

I'm burning some 8800K Astralux right now and they're pretty nice. They're a tinge whiter than the ADA bulbs, but also much cheaper.

I have the 8800K Astralux running with supplemental T5 lighting for a nighttime burst. With the Giesemann midday T5s running along-side the 8800K, the color is perfect.

[CmLaracy]

Originally Posted by epicfish

I'm burning some 8800K Astralux right now and they're pretty nice. They're a tinge whiter than the ADA bulbs, but also much cheaper.

I have the 8800K Astralux running with supplemental T5 lighting for a nighttime burst. With the Giesemann midday T5s running along-side the 8800K, the color is perfect.

Sounds like a nice combo! They're 8000K's btw

[tirtha1979]

Thanks for all of your kind response. I have a small confusion here. You all are using 8000K or Higher. But don't you think, the Blue spectrum will be much higher than Red? If I stick to Only 8000K or Higher Astralux.... what about the red plants???

[CmLaracy]

red plants will look nicer under a nice 10000K than they will under a 6700K. 10000K's really don't have a whole ton of blue.

[fishyman]

can any one provide the spectral distribution of of this MH

[tirtha1979]

Spectral distribution of this lamp is not available in Net and not in Astralux site even.

[defdac]

But don't you think, the Blue spectrum will be much higher than Red?

The way Kelvin is calculated for light sources makes it impossible for anyone to say anything about the color of the light if you only have the Kelvin-measure. Look at the Planckian locus:
Color temperature - Wikipedia, the free encyclopedia
The problem is that the locus is not just a fine line but a very broad line. Look for example at the 10000K mark - it spans colors from green to blue to white to purple.