[hahnmeister]

Here is a list of the 'bad info' you have posted...

1.

Originally posted by jcltok
I agree with all of the suggestions - since we do not have first hand information of your corals' needs.

In terms of lighting, consider whether they are getting enough light - enough lumen - you need about 15 per square inch. Next is spectrum - is the light covering the 400nm to 700nm in a balanced way? Finally, is there enough PAR - 1200 micrMols/m2/sec is the right amount.

and the correction you made doesnt help...

Originally posted by jcltok
oops. I intended to say 1800 microMols/m2/sec of PAR.

2. In this thread:

Originally posted by jcltok
The other is PAR - you need 1800 microMol/m2/sec. Any quantum meter will show you. You have to be careful about lights that achieve high PAR by boosting the violet/blue spectrum at the expense of the rest. A balanced spectrum is needed.

You can define better or worse balanced spectrum by looking at the CCT. The CCT of many high Kelvin MH are around .26 X .26 which is too far away from a balanced spectrum. Certain deeply growing corals will do fine, but it makes it tougher to raise a larger range of coral.

A CCT of about .31 X.31 is more appropriate when you have corals that normally grow in a wider range of depths.

3.

Originally posted by jcltok
What is the depth of a 30 gallon tank? Light output is inversely proportional to distance. If your tank is less than 2 feet tall, then I suggest about 1200 lumen per square foot.

Watts are not the important question - the real question is how much light are you getting at water level? A bulb may be more efficient at turning electricity into light, so watts are not a useful guide.

Second question is what is the PAR. Better PAR with a balanced spectrum produces a better aquatic environment.


Heat from the lights is likely to be an issue with 30 gallons - make sure you find a way of getting that heat away from the water.

4.

Originally posted by jcltok
...1. You replace 175 w MH bulbs every six to eight months due to phosphor degradation. Using $75 for each bulb as an average, and having two bulbs in one hood, means $300 a year more or less. 2 96w Actinics at $30 each every six months adds $120. You are now spending around $420 just for the bulbs annually.

5.

Originally posted by jcltok
By the way, the sun produces 1800 microMols/2m/sec of PAR. So the fluorescents at 200 to 350 PAR are a little low compared to 1800.

6.

Originally posted by jcltok
I am not a physicist, but as a manufacturer of LED lighting, I can respond to your statements and questions.

...3. You seem to confuse PAR with light output. They related but not the same. Light output is based on lumen and can be measured by a lux meter and then converted to lumen. You can also use a lumen meter to measure if the instrument has that function.

4. PAR has been used in reef lights because of research by Ryther at Woods Hole Oceanographic on plankton showing the lighting needs of the plankton algae which happen to be the same species of the symbiotic algae found in stony corals. PAR, measured with a quantum meter, should measure the output of evenly distributed 400nm to 700 nm wavelengths. PAR has been manipulated as you state. Many MH manufacturers add exceptional amounts of violet/blue phosphors at the expense (lack) of other wavelengths, to manipulate the quantum/PAR meter into reading higher PAR.

5. PAR manipulation success depends heavily on the ignorance of users and their unwillingness to publish even their manipulated PAR results. Why? Because sea water level PAR should be about 1700 microMols/m2/sec and the manipulators are putting out maybe 300 or 600 PAR. The PAR of LEDs can also be manipulated by adding more blue color LEDs and minimizing the count of white LEDs. The same logic applies to adding phosphors to MH to manipulate PAR. That is why you see deep blue but very low light LED fixtures. The trade off is lower manufacturing costs, higher Kelvin ratings and faint light.

6. Lumen out put at sea level is 2600 lumen per square foot or 18 lumen per square inch. Lumen and PAR should be measured at the water level, and not at the source. The reason is that light output is inversely proportional to the distance it travels - the farther the light is, the dimmer it is. So high lumen - brightness is necessary. MH will reduce their light output and change spectrum very quickly which is why they should be replaced every six/eight months. LEDs if kept at proper operating temperatures, do not change lumen or spectrum until after 30,000 hours - assuming you buy the best product.


7. Kelvin ratings are a measure of COLOR COORDINATE TEMPERATUREs which can be measured by instrumentation. Higher Kelvin does not mean better PAR. Higher KELVIN means bluer light. Why is this relevant? Because corals grow at different depths and some grow in the violet/blue light - hobbyists think that is what they need and it looks cool! Unfortunately many corals live in a higher water level and do not get the spectrum they need. Also actinics make corals fluoresce and therefore leads people to bluer lights.

10. Spectral graphs are provide in "relative output" - in other words the proportion of one wavelength in comparison to others. In high Kelvin MH you see a huge spike in blue and minimal in the rest of the spectrum. In LEDS, you can expect a spike in the blue, a dip in the 475nm range, a rise in the 500nm tapering off to near infrared. (700nm). LEDs are not the perfect solution either - they happen to be better than MH and Fluorescents. Keep in mind that what I have stated above assumes the best LED available and not just any LED. I have not stated which LED is best on the basis of published data because that is not appropriate in this forum! I can be reached at jcltok@cox.net

7.

Originally posted by jcltok
I think this where the confusion lies:


"Radiance flux (ФЄ) is the energy per unit time (dQ/dt) that is radiated from a source with the range of .01 to 1000 μm4, which includes the visible, infra-red and U.V regions. A radiant flux of 1 watt means that the source produces 1 joule of energy per second."

So radiance flux measure a WIDE range of energy that is not good to or useful to coral photosynthesis. I have no interest in the visual aspects of light when I speak of lumen - I focus on the photosynthetic range which also happens to be 400nm to 700nm.

PAR meters - "Quantum sensors measure light energy at the specific wavelengths plants actually use for photosynthesis. All quantum meters measure Photosynthetic Photon Flux (PPF) as µmol 2m-s for Photosynthetically Active Radiation (PAR) in the range of 400 to 700 nm. The meter approximates radiation between 400 and 700 nanometers(PAR) as umol m2-s."

Mind that you can fool a PAR meter by loading on one wavelength. It is unethical but it is being done.

I hope this helps the discussion and explains why I suggest PAR and good Lumen/Lux meters for measuring what light is getting to the water. To me what is being radiated is not important if by the time it gets to the water, it is minimal amounts of energy - there are so many variables that radiance cannot be applied consistently (2 units produce the same radiance, but one is hung 12 inches above he water and the other is hung 18 inches - same amount of radiance but different impact at the water).

What is important is what is happening at the water. Let me also clarify that I do believe different corals need different PAR and lumen - I just haven't seen academic research showing the PAR requirements for each type coral.

I am sure Dana Riddle lives up to his reputation and would urge him to publish in the academic world so we can all see his methodology and analysis. With his experiments, Marine Biology would gain much.

Regards,

And then everything you have posted here since.