Lighting (k) and growth

[loismustdie]

For a while, I was running my tank with XM 10k in the middle and 2 XM15k on the sides. 3 bulbs total. All 250 watt SE on Icecap ballasts and luminarc minis. My coral on the sides which were primarily under the 15k made noticable growth patterns towards the center of the tank, as if they were reaching for the 10k. I decided to pull the higher k bulbs and have all 10k and replaced my actinic supplement lighting. The growth patterns noticably evened out. This pic shows the coral a couple of weeks after I put 10k's all around. You can see how it was growing towards the middle of the tank and after replacing the 15k's, I had a massive growth spurt over the rest of the coral.
Has anyone else experienced this.

 

[prattreef]

I would say this is pretty normal. XM 15Ks are really pretty dim PAR wise. I would expect this to be less of a phenomenon with other 14K lamps, but corals that want more light, will "reach" for it if they sense it is available.

Randy

 

[TimberTDI]

Does this mean that the 20k would have even less par? I'm currently running 10k and I'm not really crazy about the coloring. I would like to switch back to 20K.

Steven

EDIT:What if I switched out from 250w SE 10k to HQI 250w 20k?

 

[loismustdie]

Steven, the XM 15k is a really lousy PAR bulb. XM 20 are better.
So Randy, if I put a 10k next to your 14k, are you saying they won't grow towards the 10k?
I did the 20k as well. I'm with rich and steve (stingnyc) on this one... 10k and actinics for me.

 

[meschaefer]

If you havn't been to Sanjay Joshie's website, you need to take a look. He has everything serachable by bulb and ballast. Generally speaking...there are lots of exceptions, but 10K bulbs have higher Par then higher color temp bulbs (14K..20K).

I run 10K bulbs with supplmental actinic lighting. What is interesting is that I just replaced my bulbs, both of wich where long overdue. One was older than the other, and my corals where growing toward the younger bulb.