XM 20K vs Ushio 10K color difference

My metal halide bulbs were getting old and I decided it was time for a change.
I originally bought some Ushio 10K metal halides based on a couple of reviews that I had read. They suggested that the quality, PAR values and color were good for reef tanks and could be used for a wide variety of corals. I was not dissapointed. They have been working without problems with an excellent white, crisp color for longer than they really should be for a reef tank :
So, after reading more reviews and studying some data provided by Sanjay Joshi, Ph.D. Advanced Aquarist's Online Magazine - Feature Article: Spectral Analysis of XM 15000K Metal Halide Lamps
I decided on an XM 250 watt 20K bulb. It actually had a higher PAR value than the XM 15K bulb on a magnetic ballast. Here is a side by side comparison of the bulbs. It almost makes the Ushio bulb look yellow.



Comments anyone?

Jim

 

Looks nice but 20K is kinda to blue for me. Did you look at XM-10,000K with 137 PPDF. Almost twice the 20K @ 74 PPDF.

 

Yes, I did think about that...
Right now I am not keeping any super light demanding corals, and I wanted something a little on the blue side. And after reading a couple of posts here from people who had bought the XM 20K bulbs I got the impression that they were not as blue as most of the other 20K bulbs on the market. That and the fact that they had a higher PAR value than the 15K bulbs is pretty much why I decided to go with them.
I guess time will tell if they work out for me. Right now I like the change in color, and I will be looking for changes in the corals. I lowered the canopy 3 inches last night


Jim

 

Well, I guess tha is good reason