Frequently Asked Questions and General Help

Q: What is the difference between Mog and Mogul Base sockets?
A: The base of the metal halide bulb usually 175 Watt through 400 Watt. The diameter is roughly 2". The US standard is size E39 and the European standard is E40. The E39 base is slightly larger than the E40 base. Usually there are few problems screwing in the European E40 base lamp into the US E39 socket. The reverse of this is not true.

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Q: What is color temperature or Kelvin?
A: Color temperature, expressed in Kelvins (K) is one way to describe color tone. The higher the color temperature, the bluer the light appears.

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Q: How do Metal Halide bulbs work and why are they different colors?
A: Metal halide lamps operate by passing an electric arc through an arc tube that excites particles in the arc tube. When the metal particles reach an excited state they emit energy in the form of visible light. It takes 100 hours of operation before the metal particles stabilize and become a consistent color. All metal halides require 100 hours of operation before color and light output stabilize. All metal halides inherently have a slight color variation between individual lamps.

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Q: Why do 20,000K bulb all have different colors? Shouldn't they all be the same if they're marked "20,000K"??
A: Color Temperature ratings (i.e. "K") is more of a marketing term than a true scientific measurement for color. There are far too many variables when it comes to an accurate "K" rating. Bulbs of the same manufacture can color up differently over time, as the ballast ages (although this is generally not noticeable by the aquarist). This is why most "K" is used as a reference rather than an absolute. The higher the K, generally the more "blue" the bulb becomes. Sunlight is about 5,500K.

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Q: All these color temperatures seem confusing. Which one should I go with?
A: Always ask yourself what's most important to you and your tank specimens. If you are an SPS keeper, and your goal is growth, then we suggest 250W or 400W Iwasaki 6,500K bulbs. If you have lower light corals and want a "deep water" look, then go with a 20,000K bulb. If you want "crisp white", then go with a Ushio 10,000K. Just remember that any new bulb that you have never tried will look different to you, as you've grown accustomed to the previous type. Visual color is a matter of personal preference.

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Q: What are the ANSI codes for Probe Start and Pulse Start ballasts?
A: Probe Start ANSI Codes for Metal Halide lamps: M102=150W, M57=175W, M58=250W, M59=400W, M47=1,000W.
Pulse Start ANSI Codes for Metal Halide lamps: M85=70W HQI, M81=150W HQI, M137=175W, M138=250W, M135=400W.

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