About to change the halides after over a year of good service and quite surprised to discover such a difference in the visible output and colour from two differing manufacturers! Excuse the poor photo,but even on this small scale i think you'll see a difference.One is 14000k,the other 16000k.Like you i have always thought the higher the kelvin the more towards a blue spectrum the light will appear,granted the left hand bulb is a year old .It is 14000k,definetely blue,made the coralline go nuts and gives a great look when balanced with the actinics.I will point out now this is not a preference but an observation.The right hand is new out of the box,not burnt in and rated at 16000k.hard pressed to see much blue on initial view,it is clear crisp white light and casts a vivid daylight shadow turning the coralline rock bright red as opposed to the purple cast from the 14000. It's not hard to see that the output on the new one is greater but this could be just that,its new! As you know you get used to the look of your own tank,and the lighting is personal and subjective.Maybe our eyes are the best judge,not a number on a box. Left bulb aquaconnect 14000k Right bulb aquamedic 16000k

Interesting observation, and very true.

Can take a few weeks for them to burn in before you find out the real colour.

Not very experienced with halide bulbs, but I did find the aquaconnect a quality, well priced brand.

Had the same happen, still using 14k but different brand total different colour, also had a faulty one had to replace it.

From what i have read 14k seems to be a very subjective colour rating and can cover anything from 12k through to 20k but what the hay i run 14k bulbs and am very happy with the colour.

Dave

I think 14k is a good option.I still run my blue tubes for affect.

i've just ordered 2 x 250W 14K's. Am going to get a 400W 20K for the middle of the tank at a later date. Couldnt decide 10K or 20K so went somewhere in the middle and just hope it'll look good. If not, bummer!

Kelvin ratings on bulbs are close to a joke. There is way too much variation between manufactures to compare. You really have to find a bulb you like through trial and error.

I used to run Venture 10k bulbs (which many say is more like a 15k bulb), put them next to Coralvue 20k and you can't see too much difference, just a tad more blue.

Layton

so long as it's bright and shiny and makes my corals grow im happy

westy1 put some pic's of your tank up looks good from the little i can see!

What I don't get is how kelvin ratings can differ. It's supposed to be the overall color compared to the color of some material heated to X kelvin, right? So, variations in the specific spectrum shouldn't matter(As far as Kelvin rating) as long as the overall color is the same? Seems the same as different company's thermometers having 30°C at different temperatures.

Good point Ira, I read an article about this, and the whole thing is actually more complex than one might think. The reason is that a good aquarium bulb, will in fact emit a range of colors, both for coral health, and viewer satisfaction. Therefore arriving at a kelvin rating can be subjective.

Bottom line is what Chimera said - "so long as it's bright and shiny and makes my corals grow im happy"

It's supposed to be the overall color compared to the color of some material heated to X kelvin, right?

What material? All compounds have different line spectra when heated, which means they give off different coloured light. It's quantum physics and electron state stuff.

A spectral analysis with an average wavelength would be a better way of comparing bulbs.

After a few minutes of research, it's compared to a block of carbon.

The problem with Kelvin temperature measurement for bulbs, comes from quantum physics, and the fact that the wavelengths (light colour) emitted by the bulb are discrete.

This means that the power spectral density is not uniform. This non uniformity means that it is not accurate to compare the colour to a uniform black body radiator.

For those wondering what a power spectral density is here is one:

cant't find the link, but have read a couple of times that the light output/color can change heaps depending on what way the bulb is facing.

on all bulbs (not sure on single ended) the have a nipple in the center of the bulb. This nipple should be facing up.

If it is not the output can vary slightly.

just what i read, i think it was on wet web media by fenner???

somone may have the link

Swapped the 16000k bulbs for 20000k,and compared them to the old 14000k,very little difference in colour ,possibly slightly bluer,but neglible,so an aquaconnect 14=an aquamedic 20,who would have guessed?

That tank is far to NEAT looking I might have to come round & stir it up a bit

Shaken not stirred!

Bleah, boooring, I wanna see some soft corals and LPS.

Nice tank westy, impressive.

Looking really nice. Interesting about the bulbs. Have your tried 10k? Be interested to see how they look side by side.

Pie