Hi,
I was reading the article 'Tips for Coral Farming', by Dana Riddle, in the latest Journal of MaquaCulture and in the article he said that you could use low K MH bulbs for grow out lights. So I e-mailed him with a couple questions and Mr. Riddle kindly answer them (in the text following this e-mail). I just thought people would be interested in it.
Basically I think he says we can use cheaper lower K MH bulbs for grow out but for our viewing pleasure we should use the normal higher K reef bulbs.
Cheers,
Victor Eng Vancouver, British Columbia, Canada
[email protected]
=================
Hi Victor,
Thanks for your message. My two years at Aquatic Wildlife was truly enjoyable and I hope my experiences there will help others.
[1. What K rating would these bulbs be? 3000/4000 or would the lowest you go be 5000K?]
The "Home Depot" metal halide lamps are typically ~4,000°K. We used one of these in an experiment over a 70 gallon Acropora system and the corals not only grew, but generated fluorescent pigments as well.
[2. With lower K bulbs (3000-5000) would the period between changing these bulbs be longer, ie. 6500K iwasaki's can be changed at 18 months but 10000K bulbs must be changed at 9 or 12 months?]
Useful lamp life varies between brands. The Iwasaki 6,500K lamps were the lamps the lamp of choice at Aquatic Wildlife; we used the Venture 5,500K lamps as well. We "burned" some of these lamps for about 2 years, but don't really recommend it - 12 to 18 months (depending upon the number of
on/off cycles) is a reasonable life expectancy. At one time, Hamilton
Technologies sold an Ushio lamp (a "True 10K") - these lamps had a longer useful life than the Venture 10,000 and 20,000K lamps.
[Would the lower K bulbs 'blue' spectrum (needed for photosynthesis) last longer?]
No. I have some unpublished data from recent experiments using a Pulse
Amplitude Modulation meter that estimates the electron transport rates (ETR) of photosynthesis. We found the difference in ETRs between high and low kelvin lamps as non-significant. In other words, there is no advantage in using high kelvin lamps - inexpensive lamps promote the same rates of photosynthesis as high kelvin lamps. This information meshes nicely with the earlier respirometer data. The corals used in these
experiments were Fungia scutaria and Stylophora pistillata. I believe the
debate of "spectrum v. intensity" has finally been settled - intensity is
the key, and most, if not all, high kelvin lamps lose intensity more quickly than lower kelvin lamps.
I wish you the best in your coral propagation efforts. The job at AW was
the most enjoyable I've ever had. We gathered so much information there.
I'm still analyzing some of the data buried in the notebooks...
Feel free to send more questions. If I have an answer, I'm more than happy to share it with you.
Dana
I was reading the article 'Tips for Coral Farming', by Dana Riddle, in the latest Journal of MaquaCulture and in the article he said that you could use low K MH bulbs for grow out lights. So I e-mailed him with a couple questions and Mr. Riddle kindly answer them (in the text following this e-mail). I just thought people would be interested in it.
Basically I think he says we can use cheaper lower K MH bulbs for grow out but for our viewing pleasure we should use the normal higher K reef bulbs.
Cheers,
Victor Eng Vancouver, British Columbia, Canada
[email protected]
=================
Hi Victor,
Thanks for your message. My two years at Aquatic Wildlife was truly enjoyable and I hope my experiences there will help others.
[1. What K rating would these bulbs be? 3000/4000 or would the lowest you go be 5000K?]
The "Home Depot" metal halide lamps are typically ~4,000°K. We used one of these in an experiment over a 70 gallon Acropora system and the corals not only grew, but generated fluorescent pigments as well.
[2. With lower K bulbs (3000-5000) would the period between changing these bulbs be longer, ie. 6500K iwasaki's can be changed at 18 months but 10000K bulbs must be changed at 9 or 12 months?]
Useful lamp life varies between brands. The Iwasaki 6,500K lamps were the lamps the lamp of choice at Aquatic Wildlife; we used the Venture 5,500K lamps as well. We "burned" some of these lamps for about 2 years, but don't really recommend it - 12 to 18 months (depending upon the number of
on/off cycles) is a reasonable life expectancy. At one time, Hamilton
Technologies sold an Ushio lamp (a "True 10K") - these lamps had a longer useful life than the Venture 10,000 and 20,000K lamps.
[Would the lower K bulbs 'blue' spectrum (needed for photosynthesis) last longer?]
No. I have some unpublished data from recent experiments using a Pulse
Amplitude Modulation meter that estimates the electron transport rates (ETR) of photosynthesis. We found the difference in ETRs between high and low kelvin lamps as non-significant. In other words, there is no advantage in using high kelvin lamps - inexpensive lamps promote the same rates of photosynthesis as high kelvin lamps. This information meshes nicely with the earlier respirometer data. The corals used in these
experiments were Fungia scutaria and Stylophora pistillata. I believe the
debate of "spectrum v. intensity" has finally been settled - intensity is
the key, and most, if not all, high kelvin lamps lose intensity more quickly than lower kelvin lamps.
I wish you the best in your coral propagation efforts. The job at AW was
the most enjoyable I've ever had. We gathered so much information there.
I'm still analyzing some of the data buried in the notebooks...
Feel free to send more questions. If I have an answer, I'm more than happy to share it with you.
Dana
