Kelvin Rating Confusion

Discussion in 'Lighting' started by Manic, 27 Jun 2009.

  1. Manic

    Manic Moderator

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    I've been doing some research on the effect of kelvin rating on coral growth and it seems everyone has conflicting views. Most people on forums have said that a lower kelvin rating such as 6500K will grow corals faster than a 20 000K. Some of the research I did implies that the opposite is actually true, that the a 20 000K globe is the best for growth. Has anyone got any personal experience with this. I'm thinking of setting up a small experiment by placing 4 coral frags of exactly the same size, in the same system under 4 different lighting conditions and measuring the growth after a month.

    Here's some links to similar experiments:

    Advanced Aquarist's Online Magazine - Feature Article: The Best Lamp Is...

    Evaluation of artificial light regimes and substrate types for aquaria propagation of the staghorn coral Acropora solitaryensis | Coast Research Database - USC
     
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  3. viper357

    viper357 Admin MASA Contributor

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    Well I've just put 6500K globes over my tank in the hope of accelerating coral growth, but now that first article you have quoted says that either 14000K or 20000K globes produce much higher growth rates???? That pretty much goes against most of what I have read. Do you have any more links?
     
  4. FransSny

    FransSny

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    Interesting read Manic...now im more confused :p
     
  5. Stressed Eric

    Stressed Eric

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    I'm tagging along on this, from what i've read the lower 6500k lighting grows corals quicker, but promotes their browning, whereas the 20k promote colouring and limits growth, and 14k strike a balance between colour and growth. I'd love to clear this one up !
     
  6. Tony

    Tony

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    It does make sense in a way because in the case of SPS's the rate of growth is accelerated with less zooxanthellae present as the coral has time to concentrate on growth opposed to zooxanthellae production under higher kelvin ratings. We should also bear in mind that lower nutrients will also allow for the speedy growth or SPS's for the very same reason
     
  7. Reef Maniac

    Reef Maniac MASA Contributor

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    Interesting article...

    From the quoted article:

    I would imagine that the same "fickle hand of fate" which affects the survivability of the coral frags would also play the same role in the "growth speed" of the frags, but the author completely ignores this issue. In other words, if a coral has been injured whilst fragging, it would need to recover first, and it's growth rate would be stunted during this recovery period.

    From personal experience (I have one x 400W 20 000K lamp on the right hand side of my tank, and two x 400W 10 000K lamps on the middle and left hand side sections), there is better growth under the 10 000K light. Having said that, I believe that water movement plays a larger role in coral growth than the colour temperature of the light.

    This would be great if you could do it. Just try to keep ALL other parameters the same, especially water flow (which is affected greatly by differing shapes of live rock, amongst others...)

    Keep us posted.

    Hennie
     
  8. Tony

    Tony

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    I also tend to disagree with the second article to a degree as a lot of coral propagation is done by fragmentation especially with SPS's
     
  9. Jaak

    Jaak

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    Eish, now i'm also more confused!
     
  10. Manic

    Manic Thread Starter Moderator

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    I've got Anthony Calfo's book on coral propogation. Let me go read that quick and see what it says on lighting.
     
  11. Manic

    Manic Thread Starter Moderator

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    Alright so read the bit on lighting and according to Anthony Calfo the best results for a frag tank are achieved with with natural day light globes (Between 5000K - 7000K obtained from normal hardware stores) combined with actinics T5's. Without the actinics the corals wont grow properly and will look brown. Only actinic globes can provide the right wave length of light needed for the corals to grow. Even 20 000K MH don't provide this wave length

    Later on in the book he also says that for a display tank the best growth and colouration is achieved with three metal halides, one hardware store natural day light globe with a 20 000K globe on each side of the 6500K.

    This information pertains to shallow water sps corals.

    For deeper water corals you need to use a higher kelvin globe in order to prevent photo inhabilitation and bleaching. After about 20 Meters under water almost all the red light from the sun is filtered out. (I know this for a fact as whilst diving I had a little cut on my hand and the blood coming out wasn't red, its was kinda blue-green).

    This information seems a bit more along the lines of what we all think and I trust anthony calfo as all he does is grow corals.

    For sps though high water flow is just as important as lighting.
     
  12. viper357

    viper357 Admin MASA Contributor

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    So am I right in understanding that the ideal setup (for maximum coral growth) would be something like 6500K Metal Halides combined with true actinic (not 20000K) T5's?
     
  13. viper357

    viper357 Admin MASA Contributor

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