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Home » Saltwater Aquarium Supplies  » Lighting  » Light Bulbs  » Metal Halide  » Double Ended  » 150 Watt  »  150 Watt 20000K Metal Halide Bulb - Radium, Double Ended
150 Watt 20000K Metal Halide Bulb - Radium, Double Ended

150 Watt 20000K Metal Halide Bulb - Radium, Double Ended

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150 Watt 20000K Metal Halide Bulb - Radium, Double Ended Information


The German-made Radium 20000K metal halide bulb offers excellent coloration and good intensity. It is crisp-white with a strong blue tint. It brings out the fluorescent pigments in corals nicely. Fluorescent supplementation is usually not necessary, but can be used for added intensity and to simulate dawn and dusk. An electronic ballast, magnetic pulse-start ballast or magnetic HQI ballast is required to ignite this bulb. This bulb is white with a blue tint on a magnetic HQI ballast. It will burn more blue on an electronic ballast or pulse-start ballast. An excellent choice for reef tanks up to 22" deep.

Common questions/problems concerning metal halide lamps:
  1. Metal halide lamps of the same kind are different colors?
    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.
  2. The metal halide lamp fires and then either burns dull or the arc extinguishes?
    Usually the ballast and lamp are not receiving enough power. Metal halides pull a high current. Usually the problem is either there is too great a load on the circuit or the extension cords are of a small wire size and can`t handle the power needed by the ballast. Use only heavy duty extension cords and try running a ballast off a circuit from another part of the house.
  3. Do I need a cover shield between the lamp and the aquarium?
    Metal halide lamps produce a large amount of UV and also have a potential of exploding. The single ended metal halide lamps have an outer jacket which eliminates most of the UV. However, they have an inherent risk of exploding and UL requires metal halide lamps to be enclosed. On double ended lamps there is no UV shield. Double ended lamps must have a glass shield or major eye injuries including blindness may occur.
  4. Can I operate a ballast and lamp together which are designed for different wattages?
    Each wattage lamp and ballast are designed together for optimal performance and safety. If you over drive the lamp it may explode and shorten the life of the ballast and lamps. If you under drive the lamp it will also shorten the life of both components and also may explode. Do not mix different type wattages of lamps and ballasts.
NOTE: The bulb should be handled carefully. Using soft gloves is a good idea to keep finger prints off bulb. This is during installation and replacement.

Bulb Replacement Guide
Bulb Types Life of Bulb*
Normal Output Fluorescent 6-12 months
Very High Output (VHO) 6-12 months
Power Compact (PC) 9-12 months
T5 High Output (T5HO) 9-18 months
Metal Halide 9-12 months
LED (non-moonlight) ~5 years (50,000 hours)
* Manufacturer Recommendations

Manufacturer Info

Radium was founded in 1904 in Wipperfürth, situated abt. 40 km north-east from Cologne in the `Bergische Land`. Already a short time later the production of lamps with high-quality tungsten wires started here. Due to its know-how Radium advanced fast to one of the most important companies of the region and nowadays counts among one of the most experienced brand-name manufacturers of the lamp industry.
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150 Watt 20000K Metal Halide Bulb - Radium, Double Ended Reviews

Average Rating
(23 reviews)
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of 3


Reviewers Rating Excellent!

Posted: 2/11/2012 from RANDOLPH, WI UNITED STATES
5.0 5
Experience Level: Intermediate

Comments: So bright a little more white then I expected though

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excellent bulb

Reviewers Rating Excellent!

Posted: 3/2/2011 from ROME, NY UNITED STATES
5.0 5
Experience Level: Intermediate

Comments: after about 4 months of running an led fixture on my mixed reef 30 gal tank i decided to try a mh fixture due to lack of color of most of my corals. i read good things about the radium bulbs so i figured id give it a try. personnaly i like a little more blue in my tank and this bulb it the perfect combo. i dont think there is a need for actinic supplimentation but i prefer to run mine about 3hours in the morning and 3 hours at night and overlap them with the mh lighting. within 3 days, 2 for my monipora corals were starting to turn a nice purple color vs. a dull brownish orange. my frogspawn opens up 2x's as much as before. might have to frag it now. 1 think u must consider when u purchace this bulb. it is meant to be run on a magnetic hqi(m81)ballast, per the manufacturer. if u dont it will greatly reduce the par value and the longevity of the bulb. par is about 47 on a hqi ballast vs. about 37 on most electronics. if u dont plan on running this bulb on a magnetic hqi ballast dont waste your money. your better off with a hamilton or phoenix 14k for 1/2 the price, which are great bulbs also.

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Reviewers Rating Excellent!

Posted: 1/3/2011 from MEMPHIS, TN UNITED STATES
5.0 5
Experience Level: Intermediate

Comments: I dont know if it was my old lamps were getting dim or what, but these things make my corals pop.

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Nice, bright bulb

Reviewers Rating Great

Posted: 11/20/2010 from DETROIT, MI UNITED STATES
4.0 5
Experience Level: Intermediate

Comments: Nice bright very white bulb with a hint of blue. Similar to phoenix, but seems 'brighter'.

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Not bad!

Reviewers Rating Great

Posted: 1/6/2010 from PASADENA, CA UNITED STATES
4.0 5
Experience Level: Intermediate

Comments: Beautiful bulb. Think it is still breaking in a bit but otherwise I really enjoy it on my NC 28g. It is a bit different from the Phoenix 14k which I also highly recommend. I think this bulb is a bit "pinker" if that is the right word. The colour of the corals do "pop" a bit more compared to the Phoenix 14k (especially greens).

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Initial Thoughts

Reviewers Rating Excellent!

Posted: 11/19/2009 from HAILEY, ID UNITED STATES
5.0 5
Experience Level: Expert

Comments: Bulb replaced a SPS 14k in a 50g test tank. It is distinctly bluer, but not obnoxiously blue. Much brighter than I expected compared to 20k bulbs I have used in the past. It has only been in place for a few weeks now, so I cannot comment on coral health/growth effects long term. So far I love the look and I think it will be a good change.

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Great Upgrade

Reviewers Rating Excellent!

Posted: 11/3/2009 from HUNTINGTON, NY UNITED STATES
5.0 5
Experience Level: Intermediate

Comments: Added this to my JBJ 28 from the stock 14K MH. It gives off a great color not to blue and makes all the corals colors pop! My clam is loving it also. Worth the price!

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Radium 20K bulbs

Reviewers Rating Excellent!

Posted: 8/22/2009 from MEDFORD, OR UNITED STATES
5.0 5
Experience Level: Intermediate

Comments: I purchased three Radium 150 watt 20K double ended bulbs. They are excellent bulbs and really make the colors in my 210g reef tank really look great. Although the price is high I would highly recommend these bulbs. I will purchase radium bulbs again when it is time to replace these.

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Expected a bit more

Reviewers Rating Average

Posted: 4/7/2009 from GARDEN GROVE, CA UNITED STATES
3.0 5
Experience Level: Intermediate

Comments: This bulb compared to my JBJ 14k is almost exactly the same brightness and intensity, but also added a little actinic pop to my corals. I still had to install some pc actinic lights to get full color out of my corals. I should have kept my 14k and added the pc actinics as it seems to be the best combo. The 150w 20k bulb is nice, none the less. It's just not a replacement to true actinics like the 250 w bulbs.

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Outstanding Bulb

Reviewers Rating Excellent!

5.0 5
Experience Level: Expert

Comments: I have been using this type of bulb with great results for a couple years now. I find it to be the best bulb on the market to date as a 20k or Bleu. Crisp white colors and the spectrum my corals want and need. I suggest for anyone out there running a reef tank to give these a try. I am sure you will be like WOW, that's what my tank is suppose to look like! Always remember to install with dimple up. You will really appreciate this bulb! Kind regards, Saxamo

2 of 2 People found this review helpful, did you? Yes No

of 3
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