Iwasaki 250w 6500K Bulb
Pictured to the left is the Iwasaki bulb that I have used. This bulb is made by the Iwasaki Electrical Company in Japan. This bulb has a long history in the reef hobby and has survived the test of time and many tanks today are lit by them. The Iwasaki line of bulbs date way back (many years) to when the reef hobby used Mercury Vapor lighting over reef tanks. The story goes that people wanted to use a better spectrum bulb without giving up all the Mercury Vapor (typical lighting at the time) ballast (which can be expensive). I'm told that Iwasaki stepped in and made a metal halide bulb that could run on a mercury vapor ballast. This is all legend to me since it happened before I was in the reef keeping hobby. I'm also told that Iwasaki lamps rated at 250w actually use 280w to 290w - a holdover from the mercury vapor days. For example, its possible to have greenish, yellow, or bluish 10,000K bulbs. They are all rated the same, but to the eye they have different colors. In general however, the higher the color temperature the more to the blue end of the spectrum a bulbs color tends to be. 6500K bulbs in general need actinic supplementation to make the tank look nice to the eye or it will have a yellowish/greenish color. Some of the bluer 10,000K bulbs, and most 20,000K bulbs do not need actinics light because they are so blue in color. Now to make things confusing: Just because a bluish bulb looks blue, does not mean it creates more blue wavelength light than a say a yellow bulb. In fact, the 6500K bulbs actually create more blue light then a 20,000K bulb--but yet seem yellowish/greenish. Why is that? The reason is that overall the 6500K bulb produces more light in all spectrums: more blue, more green, more yellow. The color temperature of bulbs can reasonably be used to simulate different depths on the reefs. 6500K bulbs being full spectrum can be used to simulate the shallow waters of the reef crest. 10,000K bulbs could be used for the mid range of 15 meters depth perhaps. And 20,000K bulbs can be used for real deep simulation of say 30 meters or more. Metal Halide bulbs have an internal nipple which usually must always face upward. If you fail to do this the bulb may not light, or it could flicker. This seems to be very important when using electronic ballast to power your metal halide lights. (Actually, the nipple itself does nothing, its just a reference. However, the glass bulb has an internal vessel that has a slope. This slope is upward from left to right if the base of the bulb was on your left side.) |
Metal Halide Nipple Orientation
Metal Halide bulbs have an internal nipple which usually must always face upward. If you fail to do this the bulb may not light, or it could flicker. This seems to be very important when using electronic ballast to power your metal halide lights. (Actually, the nipple itself does nothing, its just a reference. However, the glass bulb has an internal vessel that has a slope. This slope is upward from left to right if the base of the bulb was on your left side.) |