12000K vrs 20.000K

[Seaquest]

Hi


I brought this topic up the other night on the chat regarding the slow change coming down the road by advanced reef keepers who keep SPS corals only in ther tanks. We are seeing more and more keepers using the 20.000k bulb over any other type. I can see as a diver for 20 years hat the blue spectrum is more dominant at depth on many reefs below 60 feet. I my self have changed over from Sunburst 12000K metal halide to the newer 20.000k 400 watt Radium bulbs and I can tell you my SPS corals have shown a significant growth increase. I know I know! many of you may say its to blue but realy its not. I would like to hear from other reef keepers who agree or disagree. There is a new article about this on Aquarium Frontiers.

Have a great day

SeaQuest

Toronto

[Reefmaster]

hmm. doesn't that article in aquarium frontiers say that they found no correlation or even discernible difference in photosynthesis with higher K bulbs? maybe i'm thinking of a different article.

my honest opinion is that the high K bulbs are becoming a thing of the past, especially those that are nearly monochromatic as i understand the 12,000K are. this is simply my opinion, but i believe a large part of the hype over the past few years of moving towards high K bulbs was driven by marketing. the 5500K was standard, then came the 6500 and everybody liked the crisper colour, then they tried out a 10,000K and that was followed by the 20,000K. is a 50,000K next? hey, i could put a black light on my tank! all the while it is the newest and greatest and there are no long term studies so its easy for them to say "hey your corals will do great" with no contradictions.

i agree, blue is the dominant spectrum at depths of 60', but i'm not sure any of my corals come from that depth. so i figure the pendulum will swing the other way very soon and people will come back to the 6500K range as it may more closely mimic natural conditions for most reef tanks.
just my thoughts. shane

[Aquattro]

Shane, that was my understanding of the article as well. I believe most of the high K bulbs are popular for aesthetic reasons, not technical reasons. I use 10k bulbs because I like the look, but when I replace them I'll be going to 65k with more actinics (if required for looks).
I don't know how spectrum affects pigmentation or growth rates, but my understanding is that even if a bulb looks yellow, it still has a blue component. The yellow just hides it from our eyes. A 10k just has the yellow removed (in very basic terms).
I think as more people question lighting practices, we'll see some significant changes.