Metal Halide - 10kk vs 65k

Metal Halide Bulb Coloration - 10000k ~vs~ 65k
By Doug Wojtczak - June 2, 2001

With all of the recent interest in the color of Iwasaki 6500 kelvin bulbs and the German 10000 kelvin bulbs I decided to take a couple of pictures to show the difference.

The pictures were taken after the bulbs had at least a half hour to warm up with the camera on a tripod in auto mode and the actinic lighting was turned off.

Iwasaki 400 watt MH Bulbs

10000 kelvin 400 watt MH bulbs

As you can see the top picture with the Iwasaki bulbs makes the appearance of the colors seem much more brown and the overall color of the tank looks somewhat yellow. The blue background on the tank does look a little green when using these bulbs.

In the bottom picture with the 10000k bulbs the brown corals have a greenish tint and the blues of the clams are more dominant and less washed out. The blue background does appear more blue and closer to the real color.

As far as which bulb is better I cannot say but I do feel that if you want the fastest growth from your corals the Iwasaki's are probably the best choice and for coloration the 10000k bulbs would be the better option. After talking with the owner of Reef Dweller in Chicago who has a large coral propagation business he said that for the fastest growth he uses Iwasaki 400 watt MH bulbs over his propagation tanks and for the best looks he uses 400 watt 10000k MH bulbs over his show tank. He was able to show me the large visual color difference between frags grown in his propagation system and ones from the same colony in his show tank. While all of his corals looked good under both lights the blues. purples and greens were much more dominant in his show tank than they were in the propagation systems and the overall look was much more appealing to my eyes.

While I was experimenting with my bulbs I was able to make the Iwasaki bulbs look similar to the 10000k bulbs by using 4-110 watt Actinic VHO's along with them. There was still a very slight yellow tint but the overall look was decent.

I wish that I could offer some concrete evidence on which bulbs that you should choose but it will depend on what you are trying to accomplish and the look that you like best.

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