Lighting Question
- Thread starter Hypostomus
- Start date
absolutely right, for simplicity I am jumping the in-between steps for the calculations. the linking value is the energy needed to sustain an electron transport in the tissue of the corals, this is ~350µMOL at peak efficiency. So the question is, what is the power source that would create the intensity that creates the 350µMOL value. The answer to that is ~200watts of 440-480nm light output.
The source information is outlined in this thread: http://reefs.org/phpBB2/viewtopic.php?t=49168
The source information is outlined in this thread: http://reefs.org/phpBB2/viewtopic.php?t=49168
I guess I still don't follow...
Irradiance levels in regards to PAR (Photosynthetically Available Radiation) are generally indicated as PPFD (Photosynthetic Photon Flux Density) - given as µMOL/m^2/sec or µEinsteins/m^2/sec. Are you just cancelling out the area component and the time component here?
Even so, the watts you're referring to would be the actual light energy the coral is receiving, which doesn't necessarily have much to do with how much power our light fixtures are consuming. There are so many variables between how much energy a light fixture consumes and how much light is falling on a given coral in our tanks, I don't see how we could make much of a useful assumption from this.
IMO the only way to know how much light is getting to the coral would be to measure it with a PAR meter. Mike Kirda did just that in this study:
http://www.advancedaquarist.com/issues/august2003/feature.htm
Irradiance levels in regards to PAR (Photosynthetically Available Radiation) are generally indicated as PPFD (Photosynthetic Photon Flux Density) - given as µMOL/m^2/sec or µEinsteins/m^2/sec. Are you just cancelling out the area component and the time component here?
Even so, the watts you're referring to would be the actual light energy the coral is receiving, which doesn't necessarily have much to do with how much power our light fixtures are consuming. There are so many variables between how much energy a light fixture consumes and how much light is falling on a given coral in our tanks, I don't see how we could make much of a useful assumption from this.
IMO the only way to know how much light is getting to the coral would be to measure it with a PAR meter. Mike Kirda did just that in this study:
http://www.advancedaquarist.com/issues/august2003/feature.htm
That article is very interesting. A lot of good info there. I'm not sure I see how he arrives at his conclusion however. His data seems to represent accurately that the lower wavelength light retains its intensity almost twice as efficient as the higher wavelength light. In his conclusion though, he states that,
"250W metal halide bulbs in the 6500K to 10,000K range should provide enough light to bathe the bottom of the tank with a light field of 250 μE/m2 or so. Deeper tanks, or tanks with higher Kelvin temperature bulbs may require higher wattages to reach these levels of intensity. "
whereas his data set shows conflicting information as shown in the attachement:
"250W metal halide bulbs in the 6500K to 10,000K range should provide enough light to bathe the bottom of the tank with a light field of 250 μE/m2 or so. Deeper tanks, or tanks with higher Kelvin temperature bulbs may require higher wattages to reach these levels of intensity. "
whereas his data set shows conflicting information as shown in the attachement:
Attachments
Hypostomus - to give you a simple answer to your question the answer is no like mountainbiker619 said. But you need enough light. For my experiences I had a 75 gallon with 6 vhos(3 aquasun and 3 actinic) and I was able to grow just about any coral I wanted with excellent color at all but the bottom of my tank which I reserved for lps and montis.
Well, his chart seems to show that under 1 meter of water (Type1A) 450nm light reaches the bottom with 97.4% of its original intensity while 650nm light reaches the bottom with only 69.5% of its original intensity. So when he states that "tanks with higher Kelvin temperature bulbs may require higher wattages to reach these levels of intensity" (higher kelvin ratings produce more short wavelength light) I am confused at that reasoning.
DaisyPolyp":2z2qao95 said:
First let me say that IMO, manufacturers' kelvin ratings are fairly meaningless and I wouldn't use them to categorize lamps...
That said, spectral curves of most 6500K and 10000K lamps that I have seen show the largest spike in the violet or blue range. Just going from memory, I don't recall seeing any with a significant part of their output in the red wavelength, so I'm not sure I follow what you're saying.
What Mike is probably referring to is the fact that many of the aquarium lamps marketed as 20000K lamps have a low PAR output. I think most would agree that they are producing their light in the best (blue) range, just not producing much of it.
IMHO the bottom line is there are a lot of good lamp choices out there. There are plenty of lamps (6500K, 10000K and 20000K) that produce lots of light in the desirable wavelengths, but they don't all necessarily appear blue to our eyes.
like i said prior take Engineering Physics III if you want to understand lighting yourself instead of regertataing what is read/heard.. KISS...MH's is the safest way to go with tanks even small ones. i have a 20gal with 175W MH 10000k bulb (im gonna try 20000k asap though) that seems to be plenty of light for my shallow tank..This is hobby for me not a scientific experiment so i like to enjoy what i see and MH's IMO would be the way to go.. just my dos centavos
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