best lights ?please help

[slipknottin]

There are too many different important aspects of lighting, it can not be sumed up in a single measurment.

You need to look at things like PAR, lux, color spectrum, and the type of lighting (point source or diffused)

You can not say lighting would be adequate until you look at each different aspect.


The only way to get a 'good idea' of if you have enough lighting is to look at the lux (lumens per meter).

 

[mogurnda]

The only way to get a 'good idea' of if you have enough lighting is to look at the lux (lumens per meter).

I have to disagree with you there. Lux is a measure of the spectrum available to the human eye, and does not reflect PAR at all. A light can appear rather dim to your eye and be very useful for photosynthesis, and vice versa.
Furthermore, that is about as unhelpful an answer as I can think of. Is the point that Che will have to get a luxmeter to be able to make a decision about a purchase? If you aren't going to give useful information, why post?

This is an article that discusses PAR in the planted tank, but the conclusion is the same for photosynthetic marine creatures: most sources put out about 1uE/watt, so wattage is a decent measure of PAR. Metal halides give you more, NO fluorescent gives you less, and PC is in the middle. Adjust accordingly.

You still have to consider the depth and surface of the tank, but it's a start.

 

[slipknottin]

Originally posted by mogurnda

I have to disagree with you there. Lux is a measure of the spectrum available to the human eye, and does not reflect PAR at all.

Wrong. Considering the vast majority of par is visible. (btw par is NOT the light that is useful to corals either)

Furthermore, that is about as unhelpful an answer as I can think of. Is the point that Che will have to get a luxmeter to be able to make a decision about a purchase? If you aren't going to give useful information, why post?

Sorry, im not going to dignify you with a response there. Just note that your responses to this thread have hardly been the endall of useful information.

most sources put out about 1uE/watt, so wattage is a decent measure of PAR.

Uh, the difference bewteen 1 uE/watt and 1.44uE/watt is a HUGE difference.

You still have to consider the depth and surface of the tank, but it's a start.

No, its a very poor start. Far worse than looking at lumens or lux. You complain quite a bit about how poor lux is, and you believe watts/gallon is a better measurment? Who taught you this nonsense? Amazing how all of the experienced reef keepers trash watts/gallon, and all the experts (borneman, tullock, calfo) all use lumens to see if the lighting they have is adequate for their livestock.


Lets get some real references in this thread.

John Tullock- Ideally one would carry out direct measurments in the tank with an underwater lux meter. This is more difficult to do accuratly than one might expect, even assuming one has the rather expensive instrument avaliable. One way to estimate intensity is to rely upon the oldstyle method of measuring intensity in lumens and irradiance in lux.

Borneman- lux meters, in my opinion, are very important tools that should be implemented by those keeping corals.

In the past the general rule of thumb was to provide 3-5 watts of light per gallon. As with any such recommendation, there are problems with accepting this as absolute gospel. Not all light sources emit the same amount or irradiance or PAR per watt, and the point source of metal halides penetrates deeper tanks much more effetively than fluorescent lights. Perhaps obviously to some, another reason that watts per gallon is a bad measurment is in terms of total irradiance. If a coral requires, say, 14,000 lux to reach its photosynthetic saturation level of light, it does not matter how many gallons of water it sits in- if a lighting source doesn't provide this, it doesn't provide it. notice how coral saturation levels are rated in LUX, not in PAR or in watts/gallon

Now, as far as what is 'perfect lighting' or 'what light do corals need'

Anthony Calfo- Any discussion about lighting reef invertebrates needs to entertain a healthy measure of compromise. We know that many of the reef inverts commonly avaliable have sharply contrasting requirements to each other. Even individuals within the same species may be distributed widely over a reef, and as such, forbid generalizations made about lighting requirements in captivity.... Suffering coral deprived of illumination to the compensation point will starve most likely, the same holds true for the opposite (albeit rare) end of the spectrum regarding corals suffering from photoinhabition (too much light)

 

[mogurnda]

First, let me apologize for my snitty response. I was frustrated that your response was in the realm of the theoretical and not practical, which is what CHe was asking. If I was going to say anything like that, it should have been a PM. I also agree that some of my responses were not jam-packed with information. Sorry.

I have to disagree about visible vs photosynthetically usable light, though. Even more than plants, which have adapted to the green region of the spectrum (see Diana Walstead's Ecology of the Planted Aquarium), zooxanthellae absorb in the blue and red ends of the spectrum (I think Borneman deals with this, but see also AA writeup) visible and photosynthetically useful light do not match. This is a bit of a moot point, in that most aquarists use a combination of actinic and daylight bulbs to give the corals a decent spectral combination.

Nonetheless, I will need to go home and look over Borneman, Sprung&Delbeek, and re-read a few threads to try to make sense of what appears to be a conflict between what different authors say. I have tried very hard to take what all these people say and turn it into something useful for a hobbyist without sophisticated equipment, and have come up with little.

So when a person like Che asks a question I tend to use watts/gallon as a starting point, and adapt appropriately. Metal halide will give roughly 40% more useful light, in a more focused pattern, for example. If the tank is deeper, use more. In the end, though, I have yet to see anything more useful than "I have tried that and the corals grew beautifully," or some other response based on experience.

So, let's get back to the thread.

Slipknottin, you have clearly thought long and hard about the issue, so how would you proceed setting up the tank? This thread is not about lighting theory, but Che's tank.

 

[slipknottin]

Originally posted by mogurnda
zooxanthellae absorb in the blue and red ends of the spectrum

Blue than white light. Red light has induced bleaching.

I think Borneman deals with this, but see also AA writeup) visible and photosynthetically useful light do not match.

Humans can see most of the PAR. I think what you mean is that the human eye is most efficient at seeing the red green and yellow parts of the spectrum. In which case it does not neccissarily represent PAR --a bulb that outputs all of its light at 400nm would be pretty much invisible to humans, yet could have a higher PAR than a bulb that has all its output at 560 (yellow). And vica versa. A bulb can have an extremely high PAR rating, and be horrible for coral growth.

Slipknottin, you have clearly thought long and hard about the issue, so how would you proceed setting up the tank? This thread is not about lighting theory, but Che's tank.

Id spend my time researching on what exactly I want to keep, and then look at what sort of lighting other aquarists are keeping them under.

 

[mogurnda]

I was prepared to do a little reading to see how wrong I was and try to make sense of the whole thing, and ran across this sentence in Borneman's book (p328) "The basic unit of measurement of lumens is the lux, with one lux being equivalent to 1 lumen per square meter. There are even more relevant measurements of light intensity, known as photosynthetically active radiation (PAR) and photosynthetically usable radiation (PUR)."

Whatever.

In the end, we would both agree that choosing a species and finding out how people are successful with it is the best approach. Theory is only useful to a certain extent.

 

[slipknottin]

Originally posted by mogurnda
There are even more relevant measurements of light intensity, known as photosynthetically active radiation (PAR) and photosynthetically usable radiation (PUR)."

The range of PAR is from 400-700 nm, correct?

The human eye can see from 380 - 620 nm. That means the vast majority of PAR is also what is considered 'lumens'. PAR really is not much different. The real advantage is that in calculating PAR, you get the breakdown of the irradience in each wavelength, letting you know exactly what color temp the bulb will appear, and where the majority of the light in the range will fall. A PAR of 612 for instance is about as useful as a lux reading of 10,000. They give you almost the same information.

If you want an example of this, go back to that link you provided earlier that lists PAR and lumen output of many bulbs. Divide the 'rated lumens' by the 'par'. Most of the numbers will come out in the 60s. Suggesting that there is a pretty strong corelation bewteen the two.

 

[mogurnda]

Nothing if not persistent

So, after trashing PAR, it's not so bad after all? Fine. It's reasonable. But I did manage to learn a few things that neither of us knew, and thought I should pass them on.
But first, I thought I should clarify my position. I think measuring lux or PAR is much more accurate and precise (given the caveats about turbidity, bulb life and everything else that will affect a measure). But I defend watts/gallon on purely practical grounds. You will probably continue to disagree, which is fine, but try to listen to the words themselves and not read too much into them.

Who taught you this nonsense?

I'm afraid the nonsense is self taught. I spent several years as a postdoc doing fluorescence microscopy, and therefore got a lot of experience with visual wavelengths. Plus, I have read Borneman, Tullock, and Sprung&Delbeek cover to cover repeatedly. I continue to work with very precise equipment in the lab, and truly wish that there was a way to quantify light over a tank in the same way that I can quantify my experiments. In theory, you are completely right. Measuring lumens and/or PAR would be just dandy. Heck, I could even borrow a luxmeter and filters from my labmate who studies fly visual biology. Assuming the taxpayers didn't mind.

Now comes the hard part, implementation. Say I want to set up a tank, and I want to have frogspawn (random coral), and I want to apply these principles. I have a 55 standard (48X13X20), and would like to know what lights to buy in order to have it at the bottom. Assuming I can find the relevant values for different lamps, where do I find the lux/PAR range (not too little, not too much) to make it happy? As far as I know, those values are not available to hobbyists.

John Tullock tries to give some useful information in terms of lumens at the surface and the dropoff with NO bulbs in a few tank sizes, but then drops the ball by using vaguely defined terms "low" and "moderate." (actually those might not be the terms he uses, but they aren't much better). What kind of corals can go in those conditions? Well, that's where he gets vague. Maybe a leather coral in the moderate light tank, but then no more information about what kind of light corals need. Yes, there is some discussion about what they get on the reef, but that's much more that they will ever get in a tank.

The point is, for the moment there is no table available for the PAR requirements of different corals. So I can be as precise as I want, but it doesn't get me very far.

What if I go on Reef Central, and post about watts/gallon and frogspawn? I'll probably get 50 answers that will be good enough to keep the coral happy.

There's the difference. Even Borneman doesn't dismiss it completely. You posted this yourself:

In the past the general rule of thumb was to provide 3-5 watts of light per gallon. As with any such recommendation, there are problems with accepting this as absolute gospel.

If you still think I'm an idiot for using w/g as a very rough guide, so be it. I don't see much of an alternative short of finding someone who has success and making an identical copy of their system.

Here's the bit of college physics I had forgotten.
Lumen: Defined as the quantity of light emitted by 1/60 cm[2] surface area of platinum at its melting temperature (1770 C), within a solid angle of 1 steradian. (from my old physics text, it's probably the same in all of them). So, as far as I can tell, the online article that I cited above was wrong. It's true that glowing platinum was selected because of its broad spectrum and visibility to the human eye, but I can't find what the actual spectrum looks like. That means I have less of an idea how lux and PAR compare than before.

I want to go back to talking about corals and fish.