Metal halide

[Rippey]

What s the recommend k for coral tanks?

[motorslave]

Thats not a question with a cut and dried answer! There is a lot of personal taste that comes into play with lighting.
Coral grows best with a k value around 6500. But, that is very yellow light and not esthetically eppealing to most people. What you will see a lot of is folks using 10k and supplimenting with actinic. The higher the k the bluer the color. 10k is generally white allthough the degree of this can vary with different manufacturers. Also, the higher the k the slower the growth (allthough I have seen tanks with 20k lighting that have huge growth rates!)With the 20 K MH you will have a blue tinted lgiht that will make the colors of the coral really pop and you wont need any actinic supplimentatio (generally speaking). The actinic is mostly for our benefit and uses either PC or VHO set ups. HTH

Robert

[Geoff]

just to add to Robert's great post. the sun's temp is considered between 5 and 6K. the question can be why would we use anything different?

the answer is because it does not look as pretty. this is why finding the perfect bulb is totally personally based. i prefer the more natural look, while others prefer the more blue look. it is better to look at at a lot of tanks and decide which you like better.

G~

[Rippey]

3K Any thought on that spectrum?