Dumb LED question?

[johnmackay70]

I have recently replaced some of my kitchen GU15 bulbs with LED bulbs. The packages claim the color temp of these bulbs are 3500K, however, the light looks extremely blue - no yellow tone at all.

Then I decided to go look at some of the outdoor LED lighting at Home depot. They have some 20 and 30 watt units around 6500K , but again, the light looks blue - now yellow.

Why is this, is the color temp really higher and this is just a marketing thing to try to get the normal home user that is used to "warm white(yellow) light"?

 

[skriz]

If you light your tank with them, you'll likely see how yellow they really are!

 

[rsuddath3]

6500K isn't warm white. The 3500K should have some pink or yellow, but I wouldn't really expect that from 6500K

 

[johnmackay70]

I know that 6500K is not a warm white ... that was the best color temp of Metal Halide bulbs back when I started reefing in the 90s - basically a full spectrum daylight...

As for the 3500K LEDs, I did a little experiment and ran 2 bulbs in the same multi-bulb fixture, 1 GU15 normal bulb next to the GU15 LED bulb (both suposedly 3500K). I pointed them both onto white paper.

The normal bulb was a yellow-white with a hint of pink, the LED was a blue-white...no hint of yellow or blue

I am not thinking of running these in a display tank, but thought it might be interesting to try the 6500K outdoor lights over a fuge

 

[darcurr]

GIVE IT A TRY AND LET US KNOW HOW IT WORKS OUT:up:

 

[crew]

I have seen this before with my lights in my basement. I bought some 6500 because I wanted yellow (soothing) but not quite as yellow as I had before. These things were office white/blue.. very unpleasant. I don't know if there is a different spectrum used for aquariums or something but these lights are definitely towards the 14k range and nowhere near 6500

Edit: I did a little reading and found that the "white" spectrum peaks at around 5000k and anything about that get's into the blue area... doesn't make sense with aquarium lights looking yellowish at 10000k...

K rating is actually just a scale from Red to violet (ROYGBIV) for those that remember it. Red is a brighter light lumen wise but blue seems brighter to the human eye (how we are wired)

Red also doesn't have the "punch" that blue light has in terms of shining in to water.

The main difference between the two bulbs is in the kelvin ratings.. normally, the K rating in lights is the actual color of the light that is put off. With aquarium lights, the K rating refers to the filiment's color... that would explain the difference.. just what I read somewhere

 

[johnmackay70]

That is exactly what I am thinking, and I am also thinking that these lights are actually viable for reef use - of course some testing (like in my fuge) would need to be done first.

I don't actually have a tank up and running yet, but I am getting close to having everything I need. Once I do - I thnik I am going to try this in my fuge.