Clarification from FAQ's [Archive]

sublime

05-12-2011, 09:41 AM

After much debate I have finally decided I am going to try an ATS and see if I can remove my skimmer.

I know what my design approach is going to be now after reading through the entire FAQ's on this site. I was going to design a dump bucket for this but did not realize how much water needs to run over this filter. I have a 90 gallon aquarium and have 230lbs of live rock, yes that is a lot. So, I only have 60 gallons of water in the tank not including the sump/refuge which is only another 12. I plan on having a 11" wide x 10" tall screen.

Two questions:

1) Am I to understand that I need 400 gallons per hour to flow over this screen? To me that seems like a ton of flow. I was going to design a dump bucket that would dump 1/3 of gallon 3 times a minute over it but from what I have read, that is not nearly enough. 6.5 gallons per minute seems to be the minimum flow rate? This seems to me like it would be a lot of water to flow out of an 11" slotted pipe. I just need reaffirmation and clarification on this please.

2) As with anything that requires light there is always confusion. I am hearing two different things on the FAQ's. (Well reading them at least.) I should have blues and reds, 415nm-490nm for blue and 640-720nm for reds shinning as brightly as possible. However, it says not to use "actinic" lamps which seems contradictory to having the blue range of light. Also, you mention a kelvin rating of 2500-3500. I am confused on this because from what I know of photosynthesis, it is most active in the 640-720nm range and at 5500 kelvin.

So, I would like some clarification on what people have determined the best mix is and why if possible. Also, I am very tight on space and note that 12" 20w T5 bulbs are very hard to come by and there appears to only be one manufacture. Also, standard CFL bulbs at 23 watts would mean I would need 4 of them under my tank.

I have found the Colormax Coralife 20w mini compact florescent bulbs that appear to have a very good red range and even a good blue range. Would 4 of these bulbs suffice, (They are 8" long.) Or would 2 of the 50/50 bulbs and 2 of the colormax bulbs work better?

To summarize my question #2, which is confounded: A) Exactly what wavelengths of light work best and what kelvin is recommended and why? B) Will the colormax and/or 50/50 coralife 20w mini compacts work? C) Does anyone know of any 12" T5's that will work? D) Am I to understand that I need 100 watts, 50 on each side of my ATS?

Any help would be great. I just need to solve these problems and I can finalize my design.

Brandon

Floyd R Turbo

05-12-2011, 10:55 AM

A few questions

Are you still planning on doing a dump-bucket design? If that's the case, are you doing a horizontal screen, or are you dumping over a vertical screen? The dump design has many different considerations. It is definitely more complicated and there really is no benefit over a constant waterfall design (in fact there are drawbacks)

You flow calc is correct. 11" wide x 35 GPH/in = 375 so 400 is fine. Is seems like a lot of flow, but you'll be surprised at how it looks when the screen is growing out, it basically just creates a sheet of water about 1/8" thick on each side.

As for the light spectrum what you're describing in terms of the "reds and blues" makes it sound like you're building an LED scrubber. Unless you really know what you're doing, I would not suggest this.

There are 2 different types of chlorophyll that you need to 'hit', and they both have peaks in red and blue like this

http://i611.photobucket.com/albums/tt191/FloydRTurbo/Miscellaneous/ChlorophyllSpectrum.png

The K rating you want to shoot for is 2700-3500, I'm not the right person to tell you exactly why so I'll leave this to someone else. What I can tell you that based on hundreds of designs, this is the range that grows algae the best. The actinic lamps and 50/50s will not effectively grow the type of algae that you want, otherwise you would see hundreds of designs using them.

With a screen that does not match up to a readily available lamp size (like 24" or 48") then probably your best bet is to go with CFLs. 4 23W CFL sprial lamps would do perfectly, and use a good reflector (like the dome-style from HWS). You can use the CFL floodlight style too, but these are better suited for smaller scrubbers as they don't spread the light very well. The Coralife lamps would probably work, as long as the K rating is in the right range, along with a good reflector - you would need a different kind than the dome style, more of a linear reflector and the lamp would be parallel to the screen.

Another lamp you might consider is the kind that Santa Monica uses on the Nano scrubber, it's a flat quad tube so you don't lose as much light in the middle (between the lamp segments).

http://www.atlantalightbulbs.com/ecart/ ... 27.27KEIKO (http://www.atlantalightbulbs.com/ecart/10Expand.asp?ProductCode=FML27.27KEIKO)

There are several styles of this type of flat-tube, the "butterfly" one looks like a "W" and the lamp segments are little more spread out, so a reflector behind it would be more effective than the tight quad tube.

http://www.atlantalightbulbs.com/ecart/ ... 2P1D10102P (http://www.atlantalightbulbs.com/ecart/10Expand.asp?ProductCode=F102D.827.2P1D10102P)

HTH
Bud

SantaMonica

05-12-2011, 07:27 PM

4 23W CFL sprial lamps would do perfectly, and use a good reflector (like the dome-style from HWS).

Actually for a 10 X 11 screen, you will only have room for one dome reflector on each side. So I'd put a 33 watt curly-Q spiral on each side. You could try a 40 watts, but you'd need to back the bulb away a bit to stop burning.

For two bulbs on each side, you'd probably need to use the CFL spotlights.

sublime

05-18-2011, 12:57 PM

Hey all,

I am sorry for my late reply and I appreciate your quick replies. Life temporarily took me away from this project.
Just as a setup to all of this, this scrubber will go above my sump under my tank with very limited space. I have a very high powered high CFM fan running 24/7 under there to help cool things and hopefully when this thing is active will help cool A LOT. (That is my goal at least.)

First to answer the dump bucket question:
No, I am not planning on the dump bucket design. I cannot fit the proper size bucket in order to achieve the flow needed.

LED:
At this time I am not going to do an LED build. I am working on a build for my nano and the arduino controller to mimic sunrise, midday, sunset and moonrise/set. I am not going to move to LED on this thing until far down the road and a lot of research can go into finding the right combination of lighting with the proper frequencies.

Light bandwidth:
Thank you for answering my question on light bandwidth. From your chart am I to understand that finding lights that have a wide peak range of 425-490nm and 600-690nm would be the optimal ranges?

The lights I think I will choose to use with a custom built plexiglass/mylar reflector:
GE 40184 - F552D/830/4P/CD - 55 Watt - 4 Pin GR10q-4 - 3000K CFL - Light Bulb
http://www.amazon.com/GE-40184-F552D-GR ... B004EZLVN2 (http://www.amazon.com/GE-40184-F552D-GR10q-4-3000K/dp/B004EZLVN2)

Do you all think that two of those, one on each side about 3-4 inches away will be good keeping in mind the air circulation I have under there?

Kelvin:
Can anyone help explain why the chosen kelvin ratings are what they are? (Scientifically)

Any more help would great.
Brandon

Chipper

05-18-2011, 01:57 PM

Kelvin:
Can anyone help explain why the chosen kelvin ratings are what they are? (Scientifically)

Any more help would great.
Brandon

Well, Kelvin is easier to spell than centigrade, or fairenheight, or farenheight, or farhenhieght, or darn it all, see what I mean. :D This is why they standardized on Kelvin.

Kelvin Color temperatures are just the temperature of a Black Body radiator that emits light in a color spectrum when it is heated to that Kelvin Temperature.

As for the rest of what you are saying, I agree with you. These correlations to Color temperature and such don't seem to line up with what is taking place here in the light spectrum.
For instance stating 3000k is the equivalent (Black Body Radiator) of light in the Orange/Yellow band. This would fall in between the two Chloryphill color peaks given above. Seems Contradictory.
Then stating a Cool Flourescent light makes more sense to me, since "White" encompasses the Whole spectrum of light. But it's color temperature is 5000K!!!

Also 3000k is the color temperature of an "incadescent Bulb", whereas 5000k (cool bluish white) is the color temperature of horizon daylight!!!
I would think this 5000k would be the best, and then I would think that 3000k would be the worst???

Sheeeesh, what do I know, I can even spell fairenheight, uh I mean farhenheight, or whatever. :D

SantaMonica

05-18-2011, 03:54 PM

Thos bulbs lack light in the middle, but 50 watts is a lot on a 10 inch screen, so it might work. Only seen it used once, and it did not work well.

sublime

05-20-2011, 10:10 AM

So, I have been doing some research on color temperature vs wave length. I finally found a chart that helped clarify the explanations I have found.

http://www.techmind.org/colour/colourtemperatureannotated.png

I am still a little fuzzy on exactly why a 2700-3500 kelvin bulb would work best when the key light ranges are high blues and high reds. It just does not add up to me. However, if it works, it works.

I am going to continue researching what bulbs are going to be the best to light this thing and the easiest to install.

WRT to the bulbs I posted earlier, I would think that a properly built reflector would account for any dull spots in the center. Am I am being too optimistic? Also, I think that those bulbs could lend themselves to a very slim overall design.

Any more thoughts and or help on bulb choice?

Brandon

sublime

05-20-2011, 12:20 PM

I just talked to a physics professor here on campus. He assured me that if your goal is to target a wavelength, then kelvin ratings are completely unimportant and one should just look at the spectrograph of the output to determine if the light covers the desired range. This is especially true when talking about florescent lighting as the curve is not smooth but full of large peaks and long valleys. I think the fact that 2700-3500k light is working is incidental. This kelvin rating typically produces light that is dominate in the red spectrum. However, it is low in the blue spectrum. I believe is not of any benefit to specify the lighting requirements based on kelvin ratings. I believe it would be more beneficial to select a light source based on the spectrum it produces. With that said, I can understand why defaulting to a high red spectrum bulb based on the kelivn rating is common. The reality is that many bulbs people use for these scrubbers are bought at the local hardware or grocery store. These bulbs do not have a spectrograph readily available. However, if you choose a lamp with a known spectrum with peaks in the blue and red spectrum, I believe one should expect excellent results.

(This is why I initially choose the coralife colormax bulbs, they have excellent blue and red spectrum light.)

Thoughts, contradictions, comments and any other ideas are welcome and encouraged. I would like to understand this as completely as possible. Also, I am willing to perform some testing and most likely will.

Brandon

Floyd R Turbo

05-20-2011, 07:45 PM

Actually I get this question quite a bit on RC and would like a definitive scientific answer. I haven't had much time to search for it on here so if it's out there, I would like a pointer to it. So far my answer has always been it is what works best so it's mainly anecdotal, and that's just not enough for some people.

I think the fact that LED scrubbers work best with 2 deep reds to 1 blue and 1 warm white are an indication of the heavy red reliance. Also I use 3000K red/bloom lamps from Avant Garden Hydroponics and they work very well, so this would seem to confirm the above.

sublime

05-27-2011, 10:27 AM

I am thinking of giving up on the questions and just go with either
4 of these http://www.gladiatorlighting.com/produc ... GSTAR.html (http://www.gladiatorlighting.com/products/30W-R40-TOP-FLOOD-CFL-27K-LONGSTAR.html)

or 2 of these http://www.gladiatorlighting.com/produc ... V-TCP.html (http://www.gladiatorlighting.com/products/42W-SPRINGLAMP-CFL-27K-120V-TCP.html)

Which should I do? I am very very limited on space and this is hanging into my sump and the light has to be high enough and pointed down so that if the power fails, or during water changes, the sump water line doesn't touch the lamps.

Brandon

SantaMonica

05-27-2011, 11:24 AM

More smaller bulbs is always better than fewer big bulbs.

Floyd R Turbo

05-27-2011, 11:31 AM

SM, still looking for an answer on the K rating issue, is it on here somewhere, I haven't had time to look. I get the question every so often about why 2700-3000K is better than 5000 or 6500.

sublime

05-27-2011, 11:31 AM

More smaller bulbs is always better that fewer big bulbs.

Okay, thank you.

sublime

05-27-2011, 11:40 AM

SM, still looking for an answer on the K rating issue, is it on here somewhere, I haven't had time to look. I get the question every so often about why 2700-3000K is better than 5000 or 6500.

Yeah, I would love to have an answer to this but I don't have access to the Biology Department professors until Fall semester starts. I actually could shoot one of them an email that came to our last club meet to speak. I will think about doing that. If I come up with anything I will post here. Thanks for taking any time Floyd.

Rumpy Pumpy

05-27-2011, 12:26 PM

It would be interesting if someone set up two small scrubbers on one tank and lit them with bulbs of differing K to demonstrate the difference.

I'm sure SM is right about kelvin temperature, but it would be interesting to see it demonstrated.

sublime

05-27-2011, 12:59 PM

I agree. If I had the room I would do it.

SantaMonica

05-27-2011, 01:04 PM

It originally came from hydroponic grow lights which were heavy in red. Then after watching hundreds of people change their bulbs around, they always seemed to get better results in the reds.

Floyd R Turbo

05-27-2011, 01:13 PM

That's pretty much what I thought. For most people just telling them that 'this is what works best, based on real-life results' is good enough. There's just a few that insist on using their CW LEDs and 6500K lamps because they think they will hit the algae spectrums better, or they say 'it grows algae great in my tank' along with other arguments. I never have anything 'scientific' to give them in response. Just anecdotal evidence, which is plenty good for me. But I just don't want to see a bunch of people building scrubbers using inferior lights, then coming back and whining that their scrubber didn't work or couldn't do what we say it can, all the while still defending their choice in lamp. Would be nice to have the scientific ammo.

sublime

05-27-2011, 01:19 PM

What are you trying to say about us who don't like to take things at face value ;) heh :)

Floyd R Turbo

05-27-2011, 01:30 PM

Ace25

05-27-2011, 01:32 PM

Most "closet" hydroponic growers use a MH bulb which is heavy in reds during veg stages, then switch over to High Pressure Sodium, HPS, which is heavy in blues during the flowering stages.

Personally, I do not think 3500k is the ideal look, but that is a very general term, because 2 different brand 3500k bulbs can have completely different spectral outputs but still give a 3500k look. It is just easier to say "3500k" vs saying "heavy in 453nm and 660nm wavelengths" because 99.9% of the people will not have a way to even test what spectrum bulbs put out at home. Kelvin is just the look/color the light puts out as perceived to the human eye, which is very different to how plants perceive light.

sublime

05-27-2011, 01:46 PM

Chipper

05-28-2011, 04:32 AM

You know what I'm saying... :mrgreen:

Yeah I'm an engineer so I'm with ya...would like to know the 'why' but I'm sure that it will just reinforce the way it's done now. I have no reason to distrust SM's recommendations, so I pass on those without hesitation.

I am mathematician, so proving the why when we know the result is what it is all about :) -- Regardless, I also suspect it will reinforce what has already been tested and learned by the collective group. I am very glad I found this site and look forward to sharing my design when I am done.

Re: MH bulbs, I was wondering the same exact thing about them. I know MH works great on vegitation during the growth stages and a different light is typically used during bloom. However, MH is expensive and hot. I have been looking all over the place at different light setups and come to the conclusion the easiest, most cost effecient way to do this is with the cheesy ol CFL's. I wish I could afford some of the 12" T5-HO bulbs and build two 4 lamp fixtures.

Again, thanks to all who have responded.

Brandon

I have been following this thread, and I see a couple of discrepancies.
1. Not enough has been said about the Algae (green) response to the light.
2. Nothing has been said about the final perceived color of the light, when the peaks are summed together.

With that said, Here is a shocking statement that I uncovered:
---------------------

From the surface to depths of 6 m (20 ft), where the proportion of red light is the highest, the dominant group is made of the green algae, which have the same photosynthetic pigments like the land plants (they also being the ones from which land plants evolved).
Between 6 to 30 m (20 to 100 ft), where yellow light abounds, the dominant group is made of brown algae. At depths below 35 m (116 ft), the red algae find their optimum photosynthesis, in an abundance of green light. These algae have a red pigment, called phycoeritrin that masks the green chlorophyll and makes the absorption of green light possible.
----------------

With that said, I must note, that the 3000k Kelvin seems to be dominate in the RED. This is why the light appears Yellow. But it still includes a good portion of the BLUE.
The point is Turbo's Chloriphyll Chart, doesn't reveal what the final COLOR will look like, when those peaks are all summed together.

As a result from the first quote above, where it says RED is dominate for Green algae, and yellow is good for brown Algae, I would have to say that 3000k, being dominant in the red, and with considerable blue, really is the best choice after all. Darn it all, I went out and purchased 4000k bulbs, so I will see how these perform as time goes by.

SantaMonica

05-28-2011, 10:49 AM

Sounds like good reasoning to me. I have not spent much time on spectrum because there are so many other more important variables, but at least now we know.

Ace25

05-28-2011, 10:57 AM

Very good post Chipper!

To add a little info to understand your question about what kelvin does the 2 peaks give when combined together. The way bulbs are made, each Mfg has a "special sauce" of elements they put into the bulb, and when each element is excited they emit a certain wavelength in color. Each Mfg will have different ratios of elements to achieve a certain kelvin, which makes the spectral output between 2 3000k bulbs completely different, it just visually looks the same when combined. So to say that a "3000k" bulb is ideal isn't entirely accurate, but for beginners needs, overall it will emit more of the correct type of spectrum. In theory there could be a 5k bulb that is suited better because the "special sauce" includes more of the 2 elements that emit the correct blue and red spectrum. Unless we do a spectral analysis on every CFL bulb be can get our hands on to definitively say which bulb is indeed the best, for now saying 3000k seems to give the most success with the data we have from hundreds if not thousands of experiences building scrubbers.

sublime

05-29-2011, 04:40 PM

Chipper,

I do not completely understand your post. You say nothing has been said about "final perceived color of the light". Florescent lights are not true black body objects. They have very random peaks and are very scattered. The sum of all the light peaks is compared to a black body object that produces similar kelvin. This is what Ace25 was saying. Final perceived color of light just doesn't make sense to me as a statement, unless you are referring to the kelvin rating given to the bulb. (And as Ace25 pointed out is completely meaningless, which is what the physics professor told me.) For a good example, take a look at Geisman bulbs and you will see a very detailed spectrum analysis that shows you exactly what kind of light you are getting.

This is why I asked the question in the first place. Why care about Kelvin when using fluorescents when it is the wavelengths that matter. However, also, as Ace25 said, we know that a 3000k florescent will most likely be heavy in the red spectrum due to the nature of the spectrum. However, a 5000k bulb, according to the kelvin spectrum will be better balanced between blue and red, which is perhaps not what we want according to what has been said here about the colors that green algae prefer.

Chipper, I want to thank you for the post regardless. What is the source on that quote by the way? Also, it only states that the red spectrum is the strongest at that depth, it does not make reference to the strength of the other colors. My guess, is that all the other colors are strong. This would lead me to believe that the wavelengths of the light don't matter as long as there is a lot of par in the red. It doesn't even need to be red dominate, just lots of red light. Again, thanks for the folks that have contributed. I think I understand this a lot better and understand what is making these work as far as light is concerned. I have all the pieces cut and set in the shed ready to be welded, I hope I can get that done here soon. My only remaining issue is figuring out how to come up with the cash to get a mag5 to feed the darn thing since it needs so much water.

Brandon

Floyd R Turbo

05-29-2011, 06:17 PM

The thing about red at deep levels is interesting, because anyone that has been diving at that depth (100'+) knows that all you see is blue with out a dive light. I guess the red gets absorbed?

Rygh's LED builds have shown that heavy concentrations of red LEDs (deep red) seem to spur the best growth. Thus he has come up with the ratio of 2 5W Deep Red to 1 5W Blue to 1 3W Warm White. Lots of red in that mix. That would seem to support the 2700-3000K lamp standard

Ace25

06-01-2011, 08:37 AM

Just a laymens attempt to explain why the ocean is blue at certain depths.

Different wavelengths of light have different amounts of energy stored in them. This is just an example, say that Red has a stored energy of 1w, where as Blue has a stored energy of 2w. With 1w of energy, the red loses its power quickly once it hits water and just sputters out, while blue has more energy and will penetrate further into the water. This is why at depths in the ocean, it appears blue. If you look at the wavelengths of light between blue and red, you will see red has a long/slow curve where as blues have a more excited short/fast curve to it. A light will put out the same amount of blue and red photons, but it takes more energy to create the blue photons than it does red and with that extra energy the blue photons have more penetration power.

http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20101/bio%20101%20lectures/photosynthesis/photos16.gif

Seawater absorbs light much more strongly than air does, but visible light is made up of a rainbow of different wavelengths, each perceived by us as a different color. Blue light penetrates farther into seawater (giving the ocean its distinctive color). At the same time seawater absorbs red, orange, and yellow wavelengths, removing these colors only a few meters below the sea surface.

Not the most scientific answer but I hope it at least helps give a better understanding of light.

Floyd R Turbo

06-01-2011, 08:50 AM

Interesting take on the energy of light at certain wavelengths. So if you're saying is true (honestly I can't remember the physics of it all) then blue light has more energy than red light. Looking back on this chlorophyll chart

http://i611.photobucket.com/albums/tt191/FloydRTurbo/Miscellaneous/ChlorophyllSpectrum.png

It would seem logical that algae are adapted to use more blue than red due to higher energy? When you put this together with using lamps that are higher in red, like the 3000K grow lamp T5HOs I use, or Rygh's LED build that uses much more red than blue, it would seem that less blue is needed when compared to red because it is inherently more intense.

It makes sense on the surface to me, but still - no raw science supporting that conclusion. The anecdotal evidence also supports it. We're at least getting somewhere...

Chipper

06-02-2011, 05:58 AM

Just a laymens attempt to explain why the ocean is blue at certain depths.

Seawater absorbs light much more strongly than air does, but visible light is made up of a rainbow of different wavelengths, each perceived by us as a different color. Blue light penetrates farther into seawater (giving the ocean its distinctive color). At the same time seawater absorbs red, orange, and yellow wavelengths, removing these colors only a few meters below the sea surface.

Not the most scientific answer but I hope it at least helps give a better understanding of light.

I don't think this is a correct assessment of what is taking place here.
1. You see color of light because it is reflected back to your eye.
If it weren't reflected you wouldn't see it, in other words if you don't see it, it is because it is passing through.
2. Nothing to do with the "Energy Spectrum"(strictly speaking).
3. A crystal matrix of various sizes of ions and etc., is why color is reflected or passed through.

Example: Think of a peice of glass. You look at it, and you don't see color reflections, because all the light is being passed through. The light is not being "absorbed"(relative statement). It is either reflected or passed through.
Red glass reflects red light, but blue light passes through a Red glass.

The oceans appear blue, because the "Blue Spectrum" is being scattered all over the place, in other words reflected. You don't see "Red Under water", because it is not being reflected, in other words it is being passed through. It is the same with the Blue Sky - it is called "Rayleigh Scattering".

Floyd R Turbo

06-02-2011, 07:06 AM

I think your statement is true, but the light not penetrating i.e. getting absorbed also factors in here. So while it is true that the blue light gets reflected back and that's why we see the ocean/water as blue, wouldn't that be because that wavelength is not only reflected back but also the least dissipated wavelength in the spectrum as well?

Also I think you're half right on the red glass one. Yes red glass would reflect red but it would absorb all other wavelengths in the spectrum and pass a portion of the red through it depending on the incident angle and the properties of the glass. Otherwise you could put a white light on one side and a piece of paper on the other and the paper would be blue. This is why plants look green, because they reflect it.

Ace25

06-02-2011, 07:44 AM

The ocean is blue at depths not because reds are not reflected, it is because reds are simply not present in the light spectrum at all. The blue spectrum is the only spectrum left once you reach a certain depth. We have to take into account water density, absorption, etc.

Quick google search:

The Basics of Light (http://fuse.pha.jhu.edu/~wpb/spectroscopy/basics.html)

Physics experiments over the past hundred years or so have demonstrated that light has a dual nature. In many instances, it is convenient to represent light as a "particle" phenomenon, thinking of light as discrete "packets" of energy that we call photons. Now in this way of thinking, not all photons are created equal, at least in terms of how much energy they contain. Each photon of X-ray light contains a lot of energy in comparison with, say, an optical or radio photon. It is this "energy content per photon" that is one of the distinguishing characteristics of the different ranges of light described above. Even though it is not strictly correct, it is hard not to think of a beam of light as a collection of little "light bullets" all strung together in a row.

The energy of a photon is inversely propotional to its wavelength. The wavelength of a blue photon is less than that of a red photon. That makes the blue photon more energetic. Or how about this?
The energy of a photon is directly proportional to its frequency. The frequency of a blue photon is greater than that of a red photon. That makes the blue photon more energetic.

The wavelength of a photon is inversely proportional to its frequency. The the longer the wavelength, the lower the frequency. The shorter the wavelength, the higher the frequency.

There's a kind of a duality here. Photons are supposed to be massless, because otherwise they wouldn't be able to reach lightspeed (according to Newtons Law F=ma, if it applies, because to accelerate a photon to lightspeed would require imense forces).

On the other hand it's proven they have some kind of mass because scientist through several experiments have been able to see a photon transfer momentum to other particles (p = mv => momentum = mass * velocity).

Some other equations that have mass of a photon in them:

Since p = mv and p = h/?, then h/? = mv, where h is Plank's constant, and ? the wavelength of the photon.

KE = 0.5mv2, where KE is kinetic energy.

Floyd R Turbo

06-02-2011, 07:57 AM

Thanks Ace!! Great post.

Darn it, I wish RC would lift the link ban to this site. It would be one heck of a lot easier to just point to this thread. I know there are users on there that asked about this and now I have to go and repeat this info over there.

Chipper

06-02-2011, 10:41 AM

Yes red glass would reflect red but it would absorb all other wavelengths in the spectrum and pass a portion of the red through it depending on the incident angle and the properties of the glass. Otherwise you could put a white light on one side and a piece of paper on the other and the paper would be blue. This is why plants look green, because they reflect it.

I disagree.

Try this trick. Take a Blue ink Pen and write a word on a piece of paper. Then take a red pen, and scribble all over the word, until you can no longer see the Blue word that you wrote.
Now take a piece of RED Film, and lay it over the scribbled up word --- You will now clealy see the blue word you wrote, and you won't see the red scribbles at all.
This is because the BLUE is passing through RED filter/film back to your eye. Whilst the RED is being attenuated (reflected back to the paper), to the point that it apparently disappears. I say attenuated because not all color filters are perfect color filters, some attenuation takes place.

The blue is not abosrbed.

You are correct on Green plants, yes they reflect green light. Again, eventhough I am being repetitive, you only see color because it is reflected back at you. If no reflection, then no color.

Chipper

06-02-2011, 10:51 AM

Ace25

06-02-2011, 11:14 AM

Source: http://en.wikipedia.org/wiki/Underwater

With increasing depth underwater, sunlight is absorbed, and the amount of visible light diminishes. Because absorption is greater for long wavelengths (red end of the visible spectrum) than for short wavelengths (blue end of the visible spectrum), the colour spectrum is rapidly altered with increasing depth. White objects at the surface appear bluish underwater, and red objects appear dark, even black. Although light penetration will be less if water is turbid, in the very clear water of the open ocean less than 25% of the surface light reaches a depth of 10 m (33 feet). At 100 m (330 ft) the light present from the sun is about 0.5% of that at the surface.

And another good read:
http://www.physicsforums.com/showthread.php?t=73085

Chipper

06-02-2011, 11:40 AM

Let's remember, that this light spectrum we are interested in is relative to ALGAE. We shouldn't be to interested in what goes on with light in the Mariana Trench.

Algae needs Red light and Blue light to do it's thing. At algae depths of interest there is Red, Green, and Blue light.

Floyd R Turbo

06-02-2011, 12:09 PM

I agree, but it gives interesting insight into the requirement of algae with respect to the ratio of each spectrum. So if blue light is more intense and penetrating, it logically goes to say that you need less of this light than you do the red light to penetrate through layers of algae with water running over it. So I feel there is a correlation, however yes we don't really care (much) what happens at great depths. However I always feel that considering the extremes (like considering limits in mathematics/calculus) give us insight into what happens in other situations (hope that makes sense).

It still comes back to the fact that blue light power has more 'punch' than red, watt for watt, thus it still correlates well to what Rygh's LED build was seeing for growth with heavy red and a little blue.

So...are we inching closer to a comprehensive explanation (scientific) about what is the optimal spectrum for growing algae? Or are we spinning our wheels on the theory...I think we'll get there eventually...

sublime

06-02-2011, 04:53 PM

Okay, unfortunately I am out of town on vacation and cannot take the time to post a long reply to all the theory talk here. I definitely have some things to add. For example from the NOAA:

The ocean is blue because water absorbs colors in the red part of the light spectrum. Like a filter, this leaves behind colors in the blue part of the light spectrum for us to see.

The ocean may also take on green, red, or other hues as light bounces off of floating sediments and particles in the water.

Most of the ocean, however, is completely dark. Hardly any light penetrates deeper than 200 meters (656 feet), and no light penetrates deeper than 2,000 meters (3,280 feet ).

--------------------------- Moving on ----------------------------

However, I too want an answer to my original question. Not regurgitations of electromagnetic radiation theory. (That sounds way to harsh but what I mean is that the physical science of how light behaves is very well known.) What we should be focusing on is _how_ light reacts with the particular strain(s) of algae that are important when using an algae turf scrubber in a closed ecosystem like our fish and reef tanks.

So with that in mind, it would appear that a study has not be completed on the subject. If it has, the results are not known to this community. Therefore, we must perform our own study. Since it is infeasible for many of the people participating in this thread to have multiple systems running I have another idea instead.

There are two ways we could do this... we could each elect to run a particular wavelength of light in a controlled manner to create a result driven reproducible experiment. Or, I think I will create an LED lamp with optics for my tank. There will be three sections. 1 red, 1 blue and 1 mixed 50/50. After finding out which one works better I will also try an 80/20 red/blue and an 80/20 blue/red combination. The key to the 50/50 and 80/20 combos will that the 50 and 20 percent will be strong enough to illuminate the entire scrubber on their own. So, the 20 percent red will be the "1 watt per gallon" strength alone. So, the blue will be 5 times what is needed. (In the 80/20 blue/red example.) The idea is to truly prove if both or one wavelengths are needed.

Now, this only provides us with a reliable and reproducible study that we can then analyze _why_ one worked better than the other. This study will most likely only confirm what we already seem to know, that a heavy red spectrum is needed. Blue may or may not be needed. We may even find out that blue is just as important.

So, how do we figure out WHY one combo works better than another? The idea I have is to take our results to the academic community. I can get together a bio-chemist, a biologist and a physicist all in the same room with our results and really try to figure out what is going on. Obviously a report will need to be generated and some more research explaining what we have learned. That way I can take all of that information to some experts and we should be able to get a REAL COMPLETE SCIENTIFIC ANSWER to this question. However, I would much rather take hard evidence instead of anecdotal responses.

With all of that said, it sounds like I am harshing on all the people that have been posting and I AM NOT AT ALL. In fact, I am thrilled that there are some people that are just as interested in the answer to this question as I am. I hope that everyone is interested enough to help us find an answer. I think we could really contribute something to the advancement of scrubber technology. Also, I am not saying that information that is presented here is bad or not needed. Quite the opposite. We need all of this info, plus a study and even more data to take to a team of experts that together can help us formulate a final answer.

So, when I get back from my vacation in a week or so I will post back and we can figure out what we, or just I, will do about this problem in order to find the answer.

Thanks for keeping it alive folks. I was just going to drop it but now I have a renewed interest and passion to see it through. (And yes, this is a short post for me... heh :))

Brandon

Ace25

06-02-2011, 05:27 PM

Right on Sublime.. I agree, time to get back on track to the purpose. All the info I posted was just so others had a basic knowledge of how light worked and how water affects light. More general knowledge vs what the topic was supposed to be about, which I to am very interested in figuring out.

Algae Strains - To do this scientifically we first need to know the exact strain of algae we want to grow on the screens. Without knowing the strain, any data gained really can't be said about any other strain. Maybe strain A grows on the rocks/tidepool areas and receive full spectrum where as strain B grows 10' deep. They would have different lighting requirements. So figuring out a way to identify the algae strains that best grown on a screen environment is something that needs to be done, and would guess it would be the type that grow in tidepools because there is not much water between lighting and algae on an ATS.

There really is no way I can think of doing this experiment scientifically without making a custom ATS on a single display tank, beyond what you described doing. Since every tank is different, we can't just say Person A try this light combination, Person B try another one, because every ATS and tank setup are different which would give different results. Person A's results may not be the same results if tried on Person B's tank.

Now this has got me brainstorming.. The only way I can see this working is to create many "mini" ATS setups on a single display tank. You would have as many mini ATS setups as you can fit. On my setup I am thinking 4-5 small black acrylic boxes, 6" pipes/slots, all divided. I have a 55G tank as a sump, I am thinking making a "canopy" type thing out of black ABS that covers the tank, but inside the canopy there would be dividers made out of ABS to section off boxes. Then use identical pumps/PVC frame to hang the screen from that the canopy fits over, each section will have its own combination of LEDs. All blue, red, white, combo blue/red, and combo white/red. If you have 5 identical mini ATS setups running off the same sump that should give to pretty reliable data. You have to run them all at the same time though because nutrient levels in the tank will change. You can't run one configuration for a month, then a second one the next month, because the parameters of the water have changed.

Anyone else have any ideas to throw out there on how to do this experiment? :D