Toward a standard understanding of aquarium lighting

[DeeDeeK]

Light spread can also be somewhat affected by lenses (LEDs), and reflector type (FL). The directional focus of LED's actually has a bit of an advantage in that it should lose a very minimal light to restrike. The effiencey of light out put from FL can be strongly impacted by the type (or lack there of) of reflectors used. Bulbs with individual parabolic reflectors minimize light lost to restrike. This is why it's useful to know the limitations of individual light types. A T5 with a good individual reflector could be calculated at 1.5X the light output of a T8 for example.

Yes, I agree. Reflectors and lenses can be very useful. I'm building an aquarium of 16 w x 16 l x 24 h, and would like to light it evenly, with the brightness at the top not more than 4 x the brightness of the bottom. At the bottom I'd like it to be what we'd call a high light level. So I'll be hanging a light pretty high above it with a reflector which hopefully will result in a fairly narrow cone of light. Of course this messes up the inverse square rule.

If I hung an unreflected light 24" above the top of the tank, the light at the bottom will be 1/4th the strength of the light at the top. So if the light level at the top is 4x the minimum level we'd call "high" the bottom will be lit to my liking. Since this hypothetical light source is ok at 24" above the top of the aquarium, it will be good if hung with a reflector higher up, how much depending on the shape and efficiency of the reflector. If my light sources came with a useful measure like PUR, I'd be able to pick one which would work for me right now as I am writing. If my reflectors came with a little data, like how they affect the spread and strength of light, I could really narrow things down pretty easily.

I don't mean I want a tool as simple as wpg. If it were truly that simple, it would stink just as bad as wpg does. I want a handy, not too complicated tool or two as I would have with PUR and some system to describe the effect of various reflectors on the light emitted by the source they are reflecting or to describe the effect of the lens in an LED on light spread. I want this for my purposes, creative and atypical aquaria. I also think plenty of other people would make use of those tools for any number of reasons. As for people happy with wpg, for them it doesn't "stink," as I say. For them it is perfectly adequate and would never be supplanted by any other system - wattage is important to know for a variety of reasons, mostly electrical, and bulbs/tubes/leds will always be labeled with it. The system I'm trying to get people into perhaps collaborating on is strictly a planted aquarium thang and I only imagine labeling with PUR as an adjunct to wattage.

In terms of plant growth direction...plants are actually perfectly capable of correcting themselves (for the most part). Haphazardly plant some Brazilian Pennywort in a tank, and by the next day it will have the majority of it's leaves facing the light.

Well, here I totally agree. My problem is that my light source is plenty bright but much smaller than the top of the aquarium where it is located. Because of its proximity and size, it has a gradient strong enough and steep enough that the plants grow upwards at a greater and greater angle towards the center of the top of the aquarium the further they start from the center at the bottom i.e. they lean like crazy towards my small, bright, close by light source. A brighter light further away or an array of smaller lights equalling my current, single light in output, just as close as that light would solve the problem. A PUR on my current power compact fluorescent and one on my hypothetical alternatives would allow me to quickly figure out my solution.

HOB's pose two problems in terms of planted aquaria:
1. They have a strong potential to gas off the CO2 we want for our plants.
2. They provide poor circulatory flow, and thus poor distribution of nutrients.
Cannister filters, although not truly necessary, provide a lot more control over current, more options in delivery (such as lilly pipes), ability to install CO2 reactors and inline heaters, etc. Powerheads do offer a great way to supplement current however.

Once more I agree. Where the CO2 issue comes in, it is for me a creative/technical reason for filters other than HOBs. As I said, if filtration were just a matter of removing particles, NH3/NH4, NO2, and using a little carbon to suck up organics, we would have no need for anything but a HOB filter and some pre-packaged cartridges or maybe an UGF with carbon carts. However, creativity has demanded more and so we have a proliferation of means of filtration and biofiltration.

I mean to draw a parallel between lighting and filtration/circulation/CO2 supplementation/oxygenation. I've been trying to work in examples where a few more sophisticated tools than wpg would allow for more sophisticated use of lighting than simply for "adequate" light for acceptable plant growth. If that were all there is to lighting tanks - plant growth and basic illumination, wpg would be great. Just as HOBs are all we'd need for basic filtration if all we did was keep a few fish and maybe some plants which don't mind being at equilibrium with the atmosphere in terms of CO2. But we're inventive and creative and demanding, hence all the various filters; they are useful for achieving our purposes.

I certainly don't disagree with you on this, but the complexities of dealing with the variables in vast array of equipment choices out there make formulation of simple guidelines difficult.

Thanks guys. I'm sorry that I can't be more useful. XD It's been awhile since I've done serious research on aquarium lighting, so I'm a little rusty.

Well, you're being plenty useful. And yes, I agree formulating simple guidelines is difficult. I want useful guidelines and labeling, however, and believe that if I keep talking about it maybe a few people will see it as a useful and interesting thing and talk about it too. Maybe discussion, disagreement, and resolution can help us at arrive at a few, not TOO simple tools. Back to the filters - they are actually complicated and confusing to most novitiate aquarists but they jump in and sink-or-swim. I bet a measurement like PUR, some sort of useful system for labeling reflectors, and a few simple calculations like the inverse square law are actually easier to learn than it is to learn about biofiltration, biomedia, mechanical filtration, chemical filtration, cation exchange resins, charcoal, ad infinitum.

I refer folks back to Tom Barr and the Estimative Index, another useful, not too difficult tool with a bit of a learning curve. It is certainly not the wpg or fertilizer dosing - it is too difficult and too useful to really compare. It is more like the level I want to see my dream-tool(s) at for dealing with light.

 

[DeeDeeK]

I am exploring options for a new lighting scheme to replace the ugly hood with it's lopsided, greenish, fluorescent light which is too weak for the plants and growth I've been hoping to have in the pico. I may go with a home-made frame holding three standard lightbulb sockets with shop reflectors. I'll put 27w or 14w CFLs in them and probably suspend it 15" above the surface of the tank's water. The distance is to give the light a nice even spread with overlapping cones and to have the intensity of the light remain within a small range from top to bottom of the tank. The further away the lightsource, the shallower the brightness gradient i.e. light remains close to the same intensity for longer and longer intervals as one recedes from the light source. I'm not going to worry about the efficiency of the CFLs' output of peak frequencies for photosynthesis by just going for overkill - the green and yellow frequencies which most commercial CFLs emphasize because they're the frequencies the human eye perceives most acutely and reads as brightness are the least useful frequencies for photosynthesis. However, they are not USELESS, just less useful. They're about a third as potent as the reds and blues, so just light very brightly and hooray, the plants have adequate lighting. I figure 3 fourteen watt CFLs, 42 watts total, hanging 25" above the floor of the 5.5 gallon pico tank (15" above the top of the tank) will be the equivalent approximately of eight watts per gallon installed immediately above the surface of a standard 55 gallon tank (21 inches high). So, even if the CFLs have terrible spectrums for photosynthesis, they will almost certainly be delivering as much power for photosynthesis as 3 wpg of perfectly optimized spectrum lighting (which can at most be three times as effective perfectly sub-optimum spectrum lighting). Therefore, assuming CFLs output of light is close to the same intensity per watt as the mysterious "wpg" light source, my tank will have a "high" light level.

You can see, I use my familiarity with the inverse square rule of light spread in comparing a light suspended 15" above a 10" deep tank (25" from the bottom therefore) with one suspended right above a 21" deep tank (so say 22" or 23" from the bottom). I know the intensity at the bottom of both, assuming the same power light source is used in each, will be pretty close. I also know that being .6666666 times further from the light source than the surface of the water, the bottom will be about four tenths the light flux (how many photons per second) of the surface. A ratio of four to ten is a very small difference when dealing with light. With our vision and its useful vision in light within a range of one trillion to one or something like that and equally unbelievable (I don't care enough to do the research). We basically will see the tank as having even brightness from top to bottom. Yes, if we look for it, we can easily see the difference in intensity from top to bottom but our eyes and brains otherwise automatically compensate.

I don't know about photosynthetic organisms, but I'd assume they're photosynthetic response is pretty close within a gradient of light from 10 down to 4 (arbitrary units of brightness) since they cope with much shadowing and steep light gradients in many tanks and still grow well.

As for spectrum and photosynthetic response, I use my knowledge of the curves showing photosynthetic response by frequency of light and that they show that will much less useful, green and yellow frequencies as still useful - just use them at greater power than one would need with a spectrum emphasizing the frequencies with the strongest photosynthic response (about 3 times more powerful).

My knowledge that various light bulbs, fluorescent tubes, metal halides, xenon, and LEDs produce quite different amounts of light per watt to know I have a great uncertainty in guestimating that the amount of light CFLs produce per watts power is in the range of whatever (probably fluorescent) light source is the one in the measurement wpg. I decided that the variation between fluorescent sources is not great enough to throw a big monkey wrench into the works of my figurin' fer how much lighting to use.

A combination of estimating the CFL output is usefully close to the one in the mythical wpg measurement and the inverse square law which tells me the difference between 23" and 25" from a light source is not of concern in terms of photon flux lets me figure my 42wpg CFL lighting (7.6watts of CFL light per gallon) is close enough to the ideal of 8 wpg on a standard 55 gallon tank.

My knowledge of the usefulness of various frequencies of light for photosynthesis lets me know the 7.6 wpg at absolute worst would be the equivalent of 2.5 wpg of very photosynthetically useful light and because of the high proportion of green light (the light our eyes see best) most CFLs emit, at best the 7.6 wpg of CFL light would be around the equivalent of 4 to 5 wpg of very useful light. Of course, we have NO IDEA WHAT KIND OF SPECTRUM wpg implies. With a range of 1 to 3 times as useful for photosynthesis, 1 wpg of the light we might choose could be the same as 3 wpg of the ideal wpg measure. Or vice versa.

I hope this lengthy example shows how there are some very useful tools which one can employ along with some detailed knowledge (height of 55 gallon - a quite common size - tank, photosynthetic response variously to red yellow green and blue, the fact that different light sources have very different levels of efficiency in transforming watts into light so therefore wpg can vary incredibly depending on type of source) can be used along with some reasonable guesstimations to arrive at a scheme for lighting using the hobbling measure wpg, which we really can only guess the meaning of in terms of PUR delivered to the places we want it.

Fortunately, the difference from one level to another close by in the response of our eyes and (I think to some extent at least) and in the photosynthetic response of plants is not too great so my guess is that the range of light levels my guesses in estimating how to light my tank falls somewhere in the general neighborhood of the idealized wpg, close enough to get the results and look I want.

Wouldn't it be nice to have a set of measures which would take one degree of magnitude of potential error in figuring out any lighting scheme which is at variance to the basic T5s side-by-side not very far above the surface of the tank they illuminate sort of scheme?

Fortunately for me, I am strongly intuitive AND able to integrate tons of facts and figures (sloppily) effectively because of an unusual talent for memory of whatever I read (almost never forget it, but I do paraphrase a lot). This lets me feel comfortable using such a hodgepodge of things to figure out the lighting which will deliver what I want in this new scheme of mine. However, most people are not so lucky when it comes to quickly learning facts and principles about sciency things simply by reading nor are a lot of people comfortable with the amount of loosey-goosey estimation and assumptions I used in the above example. So if such a person is faced with figuring out some novel lighting arrangement, they are saddled with wpg and products (light sources mostly) with not-very-useful labeling. Think how many people must apply wpg the same from a tank 15" tall to one 30" tall or maybe even 8" tall. 3wpg at 30" is 12wpg at 15".

This is in part why we ought to be provided useful labeling with figures and measures like PUR and perhaps a little graph of the light source's spectrum. Really, we should. It wouldn't hurt, wouldn't interefere with those for whom wpg is adequate and does not stink, as I say it does. It probably wouldn't even be very difficult of costly for manufactures to adopt such labeling.

 

[DeeDeeK]

Think how many people must apply wpg the same from a tank 15" tall to one 30" tall or maybe even 8" tall. 3wpg at 30" is 12wpg at 15".

This is in part why we ought to be provided useful labeling with figures and measures like PUR and perhaps a little graph of the light source's spectrum. Really, we should. It wouldn't hurt, wouldn't interefere with those for whom wpg is adequate and does not stink, as I say it does. It probably wouldn't even be very difficult of costly for manufactures to adopt such labeling.

Quoting myself, yeah, how solipsistic (that's todays vocabulary word. If you hear anyone say it out loud today, scream as loud as you can! It's a fun game you can play with your friends!). But I like to think "out loud" in print. It really helps me organize my thoughts and integrate new facts and ideas, including those I came up with in the post previous to the one I'm writing at the time. Plus I may just tickle someone into a nice, friendly dispute or sharing of facts and interpretations which are at odds with one another's conclusions about any given subject. OR perhaps a suggestion for improved versions of hypotheses and practical tools I suggest or espouse? (Hint hint) OR even a totally new approach or tool or concept?

I've really liked everyone's feedback so far in this thread. C'mon, doesn't anyone have a scheme in the back of their mind for an aquarium setup they'd like to light nontraditionally i.e. not have an ugly rectangular lamp housing trailing an electrical cord sitting on top of the tanks nice fitted acrylic or glass top and messing up all the nice clean lines of the tank, interfering with the space it structures (this is an artistic concept, of which has to do with giving order and meaning to the subjective visual field i.e. it's about composition) within which your little fishy paradise is situated, and casting light in a possibly quite uneven manner since the source is so close to the thing illuminated and the light comes down in a cone or a triangular prism shape. Your high light plants may only thrive in the middle of the tank and the ones to the side lean inwards towards the stronger light, which is unattractive for plants to do. Or perhaps you want to get rid of that ugly hood which came with your aquarium in the box from Petco or whatever, which they sold you at the same time they sold you a bunch of wagtail platys and sickly neon tetras? You know, the wood-grain and black hood with the fluorescent tube mounted way toward the back and too weak to really do all that much good, and makes that hollow sound when you close the access panel in the front after feeding the fishies.

What I mean to say by all that bitterness is that the great majority of lighting that at least I see on tanks is displeasing to look at and ruins the nice clean space that a transparent rectangular solid shape like an aquarium (OK, it's not truly SOLID) and doesn't do justice the the contents of the aquarium because of the proximity of the light to the water and the (usually) much smaller area of its reflector(s) and light sources compared to the area of the surface of the water, which as I've said allows coverage in the form of a cone or a sort of triangular prism shape. It's really durn ugly and isn't fair to the rest of the aquarium or to the aquarist who invests so much time and care on the living contents of said tank.

ADA offers a number of attractive lighting options and while I may critique ADA unfavorably in terms of its rigid direction of the hobbyist in technical and even aesthetic aspects of setting up and keep the tank, I must say they offer a really nice line of equipment which if you can afford it, can be used however one likes and it looks pretty good and does the job well. There are other companies who offer pleasant alternatives to the ugly block-o-fluorescents resting on the canopy type lighting. Also, plenty of people are into DIY. Thing is, the light sources are often pretty different from the old T5, HO and VHO versions included. Also, they are quite frequently much higher than the couple of inches the mainstream hoods are above the surface of the water. And the spectrums they emit have different levels of various frequencies and thus different PURs even when you normalize their output by efficiency of transforming watts into light for the purpose of comparison.

So, say wpg is VERY useful on a 21" high, 55 gallon tank, when using T5 HO tubes with say, a Vitalite's spectrum output. Reasonable standard to equate wpg with, no? So how do you figure a high pressure sodium light, say at 250 watts power, you'd like hung three feet above a square, 60 gallon aquarium in terms of wpg when you want to grow low light plants which are sensitive to too much light. Is your light source too strong or hung too low? Is it's PUR per watt similar or different to your Vitalite type spectrum T5 HO tube? Do you think a lower wattage, different light source might be a good choice over the high pressure sodium based on PUR, light spread from 3 feet, and how pleasing to your eye colors are under its spectrum?

Blah blah blah, hard to follow as I through so many variables to consider but that's how it REALLY is when one lights an aquarium. Even if one simply uses wpg as a guide, those variables are at play and simply rolled into whatever circumstances, such as choice of hood and light source, there are of your project plus wpg. So you don't have any control or choice in many many aspects of your lighting which affect how things look, how your plants grow (vertically or on a slant, only directly under the light source or equally well throughout the tank), and your choices in design (hanging light, sitting on the aquarium top, clamped to the side, etc.). Yup, aquarium lighting is NEVER SIMPLE, only some approaches to it are, those too generalized to liberate the aquarist creatively.

If you've learned all about heaps of plant species and fish species and invertebrates, filters, water chemistry, fertilizers, bacteria, etc., etc., that a well-rounded aquarist knows you certainly can untangle the confusion and mystery of light and lighting. You certainly can. And I'll nag you about it every time you read my posts in this thread.

 

[DeeDeeK]

FREAKIN' REPTILE LIGHTS!!!!

A friend turned me on to special lights for reptiles, said they may be helpful because of their much more useful labelling. I'd figured that all they were was fluorescents with a bit of UVB added in or purple incandescents for nighttime, and infrared to keep 'em warm. I was so wrong!

My favorite light was a power compact, 18w, I forget the manufacturer. It had a graph on the box showing the relative strength of it's light output according to wavelength from 300 nm to 750nm. It had no UV light (light in the 300 nm range) and not much infrared but it had spikes right around the peak photosynthesis response of many plants, in the red and the blue end of the spectrum. Additionally, it had a taller peak in the green-yellow region of the best sensitivity of human vision, about 2.5 times the height of the blue and red peaks. There was a CRI (color rendering index, a decent indication of how natural and accurate colors under that particular light will be) of 98, which is very very good. Also, it had the standard color temperature rating listed but that can be completely ignored to no disadvantage at all with the other data provided.

I can look up the efficiency of power compact fluorescents, the wattage of that lamp (18w) and calculate the amount of light it makes. Then I can throw out all the frequencies other than those of the three peaks because the others come to only a fraction the amount of any of the peaks, and I can just be lazy and call the green peak 3x the height of the other two and then divide it down to 1 since the green is around 1/3 the usefulness that blue and red are. So, red=2 and blue = 2 and green =1. Let's call orange-yellow 0.5 (it's presence in the lamp's spectrum is quite minimal) and violet 0.5. Add together to arrive at 6, so we can see that red and blue each contribute 2/6 of the photosynthetically useful radiation(light), green 1/6, and the rest 1/6. By looking up efficiency, which is the %wattage which becomes light out of the lamp's total wattage, we know the total amount of light (the majority visible and therefore of some use to plants) in watts the PC fluorescent emits. We'll assume no reflector for this example and divide the PC's output in half (the other half goes up, right?). Now divide by 6. The PUR, in this extremely simplistic little method I just made up off the top of my head (so it might be pretty bogus but I hope it gives you an idea of what I'm talking about when a say "a not TOO simple, reasonably easy to use method for dealing with light") is 5/6 the wattage value of light the lamp emits - 2/6 red + 2/6 blue + 1/6 green + 0.5 orange-yellow + 0.5 violet = 6 total visual spectrum in terms of proportion of photosynthetically useful radiation (which is why green has been divided by 3 and orange-yellow and violet given such low proportions other than their low presence in the spectrum). Let's imagine it's a 60w PC (which I'm pretty sure doesn't really exist but the math is easier this way). At 20% efficiency (another figure I'm making up for convenience), that means 12 watts of the 60 become light. 6 watts shine down, so 5/6 of 6 is 5. 5 watts of light adjusted for photosynthetic response of plants by growth. Let's say the standard height to measure the amount of light reaching plants is 21", the height of a very average 55 gallon tank. Our measure is 1 watt of the adjusted light (PUR) per 11 gallons - standard height of 21". This might seem very low but remember the actual wattage of the light is 60w, so in the common usage of wattage, we'd say it is something like 1.1 wpg. Anyhow, using the inverse square law, which is really pretty easy once you get it, we can figure out the lighting from any height. Assuming that the old-fashioned 1.1 wpg of our 60 w PC over a 55 gallon tank is within the "reasonable" range of light expected from 1.1 wpg when that term is used in lighting tanks, the light level is in the low range but not too low. So, 1 watt per 11 gallons PUR is a decent low light level. It tells me that with my 14 inch tall tank with the light from this example that the light will be 2.25 times stronger at the bottom in the center of the triangular prism shape of its spread than in the "standard" tank, so will be 2.25 watts per 11 gallons equivalent PUR, well into the light levels we call "medium." The gallonage of the actual tank doesn't matter since what we're looking at is simply the level of greatest brightness at a specific distance from the light source. Looking the the strength of the light from the surface of the tank's water to the top of the substrate will tell us about the light's spread in a rule-of-thumb sort of way. The lower the contrast from top to bottom, the lower the contrast from one side to the other of the cone of spread at substrate level. So we can roughly figure in advance how many light sources of a certain type we want to use to cover the bottom in the manner we prefer (usually evenly if possible).

Was that complicated? Yes, a bit. It took me 45 minutes approximately to write the above paragraph off the top of my head with no editing. If I were planning out a really choice aquarium setup, one with great aesthetics as well as a great little mini-ecosystem and plant growth, I'd spend a lot more time than that on it. An aquarium can be a truly beautiful thing, speaking not only of the beauty of the organisms and aquascape within but also of the care and skill of the aquarist who stands beside it. In a few words, the well-rounded aquarist is a skilled craftsperson and even an artist.

As a skilled craftsperson or even an artist, doesn't every contributing element demand attention to detail, awareness of its role, and skill in deploying it? If you agree and have pride in your craft, you may consider looking into light more closely.

If a company providing products and tools for the skilled aquarist takes pride in its products, they will take a hint and look into adopting similar labeling to the labeling of reptile lights but perhaps settle on a standard for describing the adjusted output in terms of the degree of it's photosynthetic usefulness. The aquarist may wish to purchase reptile lights rather than those marketed for the aquarium market. With such a PUR rating, lumens (so we know how bright it will look to our eyes), and CRI rating the aquarist could very easily figure out how they'd like to light their tank in terms both of viewing quality and quality of vegetative growth. A rough knowledge of the inverse square rule that 2x distance = 1/4 light, 1/2 distance = 4x light, 1.5x distance = 2.25x light, 2/3 distance =0.44x light should let one guestimate closely enough within the range of common aquarium heights to light properly. Custom heights may require applying the actual, not very difficult, math.

Too much to ask of the makers (or actually re-packagers of 3rd party manufactured lights)? Not too much, apparently, for those serving the reptile keeping community. So what are we, frozen bloodworms to sell to us such drecklich labeled products?:wall:

 

[Slappy*McFish]

Your thoughts on the GE Aquarays freshwater/saltwater 9325K bulbs?

Plants seem to do very well with this light, but I personally hate the way it looks when used as a stand-alone bulb. Combined with a 6700K or 10000K bulb, however, it actually looks very nice.

With lighting, most people just try to find a nice balance of CRI (for aesthetics) and a useful spectrum that the plants require.

 

[DeeDeeK]

Well, personally, when just talking about the look of the lit aquarium, I am a sucker for the 5500K to 6700K range, so long as it's CRI is good or really, so long as I like what I see when I check out the colors under it's glow by itself. I prefer daylight-lit colors. Purely personal, but the steely aura of 9000K+ just makes me think too much of a style of music videos and car commercials from the mid-nineties. It's arbitrary and about taste - probably influence from my background as an artist has me wishing to see the full range of colors in a scene and to see them true. With taste as with underwear, to each her or his own.

I was looking at a graph of the GE aqua rays freshwater/saltwater fluorescent spectrum and saw the placement of three big spikes in spots which are far enough off from the three primary colors of emitted light (red, green, and blue) that I knew that colors would look unnatural. I sort of knew that already from the moment I read that the light "enhanced" colors. Also, any light's spectrum which is stacked away from the 5500K to 6700K either down toward the red or up toward the blue as is this product is going to show colors differently from sunlight.

I must point out that the sun's spectral output follows a smooth curve without major peaks and troughs much less extreme spikes. It is impossible that a light be truly simulating the solar spectrum unless it's spectrum approximates that curve or the choice of red, green, and blue frequencies to boost into spikes is such that they elicit the same response in our vision when lighting a fully colored scene as would the spectrum of the sun or a black body. The solar spectrum's curve is actually very close to the ideal black-body spectrum. So all frequencies in the visible spectrum are present, though not equally, but in smooth transition from one to the next. Our visual system, however, responds to wavelengths of light in such a way that using just red, green, and blue we can get it to see a very wide range of colors - though not the exact same ones seen under the light of the sun. Television tubes (remember them?) are a kind of phosphorescent lamp, with red, green, and blue phosphors which are lit up when a beam from the electron gun at the other end of the tube strikes them. Look closely at any screen, LCD, plasma, CRT, etc., that displays colors and you'll see that yellow is made from green and red phosphors side by side. Our eyes mush them together from a distance into yellow. This is why many lights are made with peaks in red, green, and blue - to show a full range of colors. Color "enhancement" is done by shifting the three prime spikes slightly out of the primary color's frequencies and/or by adding secondary, smaller spikes or stacking a close range of frequencies into a bell-curve like peak. This causes certain colors to "pop" and mutes others somewhat. Any light which "enhances" color is necessarily going to be lighting the scene in an inaccurate, unnatural manner. This may suit a particular aquarist or artist's aims and taste perfectly and be used with intention to achieve a certain end result visually but it's a shame that such lights are marketed in such a misleading way, where folks ignorant of light and color theory trust the claims made by the lights manufacturers.

I can certainly understand why you don't like GE Aquarays freshwater/saltwater 9325K bulbs (with their poor CRI of 65) when they're standing alone. The parts of the spectrum they boost are not the ones which result in a natural colorspace. Adding even a 10000K light, which has quite a bluer spectrum than the sun, probably brings up the real rgb to where you see the real colors of things. If it is a 10000K color "enhancing" light, however, it would probably look just as bad with as without it.

The color temperature of a light source is not the same as it's spectral output. Color temperature is based on the amount of photon radiation (light)emitted at every wavelength. If there is way more output in the higher frequencies, the light will look bluer and bluer. Same as for lower wavelengths pulling the color temperature down towards the red. The bluer, the higher the temp. in kelvins (the K at the end of the number for the color temperature. One could actually create two different light sources with extremely different outputs at every frequency but by adding the values for each frequency of light in the sources spectrum the same temperature Kelvin will be the color temperature for both spectra. Colors might look very different from one to the other, too.

Yes, people do just try to find a nice balance of CRI (for aesthetics) and a useful spectrum that the plants require. Or something very much like that. I've been suggesting a system which would offer a great deal of control of the light, with one thing being the ability to choose a single light source which would provide a very good amount of PUR and also light scenes brightly and well. Better tools, better results I say.

 

[wespastor]

I am still a bit befuddled about light and such things ... but here what I did on my 125 Gallon Terrarium with an enclosed 10 Gallon aquarium. The Aquarium bottom sets about 18" from the light source. The light are CFL's Standard socket. The hood is a DIY with a bathroom fix for the sockets (economical). Directly over the Aquarium are positioned two of the socket. One of them contains a 50watt CFL (200watt equivlent) (5500K) and a CRI of 90+; The one next to it is a 26watt (100watt equivlent) 6500K).

There are three other bulbs that are 26watt (100watt equivlent) 6500K) and three that are 23watt (60watt equivlent) (2700K), but these do not effect the aquarium (or at least I don't believe they do) because they are primarily over the Terrarium part and not directly over the aquarium.

So how does this light compare with what my 10 Gallon tank shouls use? ( Keep in mind I would like to continue to use those type of CFL's with the standard socket.

Thanks for the help.

Best wishes,
Wes

 

[trigiver01]

Don't forget absorption! Light is energy after all, and when it collides with matter some of its energy is taken away in the collision.

Example: water absorbs light much faster than air, which absorbs light much faster than vacuum (no matter). Also - we can't forget that different substances have their own characteristic absorption spectrum. So the inverse square law multipliers are really not any more accurate of an addendum to the wpg measure because we're multiplying a "rule of thumb" by a "rule of thumb".

Like stated many times previously, in such a nonstandard application (things like water hardness, gravel color, and any dissolved conjugated systems - e.g. blackwater will affect the spectrum present at various depths and the lumens, watts per meter, etc.), it will be extremely difficult, time consuming, and costly to develop standards for lighting specifications.

Having said that, I do agree that we need a new rule of thumb - one relating power output (note: this is different from energy in a physical sense) to surface area.

Also - lumens cannot be an accurate measure of light as it is relative to the human eye, which must experience changes in radiant flux (the actual measure of power per unit area) by factors of ten or more to be perceived as different. All of these units have specific meaning and they aren't often used correctly - which leads to lots of confusion and wrongfully drawn conclusions.

 

[excuzzzeme]

Wow! What a read! Thanks for all the postings,you all have succeeded in thoroughly confusing and losing me! I am not real big in paying attention to my light as long as a) the color rendering is aesthetically pleasing and b) The plants derive sufficient value to assist them in their growth!

However I do agree with the main topic of needing effective standardization of lighting values. The "rules" of 1" of fish per gallon of water (shudder) or the 1 wpg of lighting, is a great aid in selecting the most likely best. Though both may be way off the mark to the layman, it is a start from which to learn.

When you take out all the "fun" and start with indexing, math tables, growth factors, lighting tables, etc as prerequisites to a "properly stocked or lighted tank" you lose the average hobbyist. They are into it for the fun, not a secondary full-time headache. The more complicated you make it, the less participants you will have.

As you were, carry on.

 

[wespastor]

Wow! What a read! Thanks for all the postings,you all have succeeded in thoroughly confusing and losing me! I am not real big in paying attention to my light as long as a) the color rendering is aesthetically pleasing and b) The plants derive sufficient value to assist them in their growth!

However I do agree with the main topic of needing effective standardization of lighting values. The "rules" of 1" of fish per gallon of water (shudder) or the 1 wpg of lighting, is a great aid in selecting the most likely best. Though both may be way off the mark to the layman, it is a start from which to learn.

When you take out all the "fun" and start with indexing, math tables, growth factors, lighting tables, etc as prerequisites to a "properly stocked or lighted tank" you lose the average hobbyist. They are into it for the fun, not a secondary full-time headache. The more complicated you make it, the less participants you will have.

As you were, carry on.

I agree. Many would not even enter the hobby if it were posed to them in a complicated manner. Including me. In fact, I tell most people that wat to first enter the hobby to, "Buy a glass box, add water and stir." Over the years I have tried different things trying to find a better way. Some things worked many things failed.

Even now I am a little experimental in my practices but I try to measure and quantify and reason first before I act.

Some of my actions even take months to implement because I do research first. I try to reason and understand what's inside the box before I venture outside the box. There is nothing wrong with going outside of the norm if it is done with reasoning and understanding.

Science moves forward with hypothysis every day. And That is nothing more than thinking outside of the box.

Best wishes,
Wes