Can someone clarify Metal Halide Kelvin Ratings?

[antfarm2000]

I'm going to be placing 2 250watt MH fixtures above my 55-gallon tank.

Should I go with 5600K bulbs, or 10,000K bulbs? I know that the 10,000K bulbs are bluer, and that 20,000K bulbs are even MORE blue than that, but which looks best?

I know that this is a subjective question, but does anyone have any accurate pictures as to how these different bulbs make a tank look?

Does the 5,600K look too Yellow? does the 10,000K look too Blue?

Also, would it be wise to get 5600K bulbs, and supplement them with 40watts of actinic Flourescent (also to create dusk & dawn), or is that stupid?

[griss]

Antfarm,

I recommend against 5600K bulbs for two reasons. First, they are too yellow and even with VHO supplementation. Second, they do not have the best spectrum for coral growth.

6500K with 2-4 VHO bulbs will give you a white light with a very slight yellow tint.

10000K are crisp white light.

20000K are crisp white with a blue tint.

FWIW, many people use a NO actinic bulb (or VHO actinic for that matter) to simulate dusk to dawn. I think it is a great idea, gives the animals time to acclimate to the lights coming on/going off.


HTH,

Griss

[MalHavoc]

This page has a bunch of photos of various bulb colour combinations:

www.coralreefecosystems.com/ltg_bulb_color.htm

[brideauj]

I say go for the 10k. In fact, I will look for perhaps 12k on my next bulb purchase. Here are some photos of my 55gal reef with diffrent MH colors. Take note, your monitor settings impact color represntation severly.

This is 250W 4-5k on the left and 250W 10k on the right. with a 55W actinic on each side. 610W total.

http://www.myghia.com/fishstuff/images/bulb-colors.jpg

This is two 250W 10k bulbs with 55k actinic on each side. Again 610W total. Decent white but still a bit yellow on the Ushio bulb. A little more blue with the Coralife bulb.

http://www.myghia.com/fishstuff/images/tankpan1.jpg

Cheers