Mobile Bay Reef Keepers

When it comes to MH's, do you like 10k, 14k, or 20k, etc. better and why? Have you seen differences in you corals with one over the other bulb? Also what are the differences in them? I have 2 10k and 1 14k. I know the 14k is bluer and the 10k is whiter. I have never seen any other colors besides the 10 and 14.

Here is the little bit I know about this subject.

I started out with 2x 6,500K Iwasaki bulbs supplemented with actinic VHOs. The 6,500K looked very white with a significant amount of yellow. Don't run these unless you have good actinics to go with it. The 6,500K are VERY strong lights with nearly double the PAR as a 15,000K.

I now run 2x 10,000K XM bulbs without actinics. This looks almost the same as the previous setup even though I don't have actinics running anymore. The PAR is a little lower, but probably about twice as strong as a 20,000K bulb. Since I just started up my tank (again), I wanted the stronger PAR to get the frags to a 'normal' size quicker. I would prefer to have some actinics to supplement this lighting, but I already removed the VHOs.

Next I'll run the 15,000K XM bulbs. In my opinion, this is perfect if you don't want to run actinics.

Some people are running 20,000K bulbs, but you lose a lot of PAR. This is a VERY blue light and IMO you don't need/want actinics with them.

A couple things to understand... The higher the 'temperature' (e.g. 6,500K, 10,000K, 15,000K, 20,000K) the more blue the color and the weaker the intensity (PAR).

By the way... the 6,500K and 10,000K do not show the fluorescence of the corals very well unless you have actinics to go with them. I've seen good color with 15,000K and very good flourescence with 20,000K without actinics.

thanks for the info!!

Here (http://www.cnidarianreef.com/lamps.cfm) is the best place to help make a decision without actually seeing a bunch of halides that have been burned because they will look different after 100 hours or so. BTW, the nicest looking tank (both coral color and the overall look) used 250w 10kk Ushios.

In my experience, even the difference between the Megachrome 13K and the 14.5K in terms of par is pretty dramatic. The lower light corals like the 14.5 just fine, but the main tank definately does well with the 13K.