About Radium 20K metal halide bulb

dz6t

Acro Garden, BRS Sponsor
BRS Sponsor
BRS Member
Many fellow members ask me about Radium 20K bulbs I am running on my SPS display and high end frag tanks.
Here is a very nice summary from Premium Aquatic:
Enjoy

http://premiumaquatics.com/articles/radium

"250w Mogul Base

The 250w Mogul Base Radium is a unique lamp in that it’s actually rated as a 270w lamp and is specified to be ran off of an M80 Magnetic HQI ballast. This is one of the very few metal halide lamps on the market which are single ended that are spec’d for this particular ballast. This does not mean that the lamp can only be ran off of a magnetic M80 HQI ballast though. Other ballasts that are very common to run this lamp with are standard electronic ballasts such as the ReefBrite, old IceCap, or the Vertex ballast. With the introduction of the somewhat new “Select-a-watt” ballasts that are now on the market such as Lumatek, and even better the Luxcore brand, you can choose to run this lamp at standard 250w, closer to spec of 270w with the “250” or “250 HQI” settings that are on these select-a-watt ballasts.

When running the lamp off of a magnetic M80 HQI ballast you will pump a good amount more of white light through the lamp, which is easier to see with the naked eye. This is the result of the lamp running at a slightly higher than intended wattage, at 330w. Please note that actual wattage to the lamp will be slightly less due to power loss through the wiring. This makes the lamp have a very good mix of white and blue light, and excellent PAR numbers for a bulb that is heavier weighted to blue side of the spectrum.

Running the lamp on the standard electronic 250w ballasts will produce the most blue out of the lamp that you can get. The wattage does drop down on the lamp to approximately 245w, and the more visual white light is more subdued to the naked eye. PAR levels do decrease, but you do gain some in terms of coral coloration that is displayed.

When using an electronic ballast that has a select-a-watt setting on it and running it on the “250 HQI” you split the difference in output between a standard electronic 250w setting and the magnetic M80 HQI numbers. This gives a very good balance of blue and white mix to the lamp, and splits the difference between PAR numbers that generally equate to growth, and more blue light, which usually helps with maximum coral coloration. "
 
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