A noob question

[NHGJesusFreak]

I was just on hellolights.com, looking at 150W MH bulbs, and I was wondering how do you know to buy 10,000K, 15,000K, or 20,000K bulbs? And what is the difference?

[hypertech]

Color.

10k is pretty white. 20k is pretty blue. 15k is in the middle. I'm running a 14k bulb right now. Its really a personal preference more than anything.

[wes]

those numbers are indicative of their color. the lower the number, the more yellow the hue. generally for reefing, 10k and up is used. I like a blueish white, around 12-14k. check out http://www.advancedaquarist.com/2007/12/ and look for sanjay yoshi's articles on spectral analysis. try to pick a bulb (make sure you're looking at the right wattages and socket) that gives you the most PPFD and is the color you want. bulb choice can really make a difference.

[Turf]

Really it all comes down to what you like to look at so go look at someones's tank w/10k and one with 20k; I personally LOVE the 20k's

[gogregerson]

I've found that you get much faster SPS growth rates under 10k's compared to 20k's.

[tittan1500]

i have made a diy lightind system for 50 dollars with bulbs that puts out 156 watts of 6500 k and then added 2 18 watt antics it works good