purple bulbs - effects on corals, algae?

[ReeferBatman]

Bear in mind Its early Sunday morning and I've had a few, however... If I understand what you are claiming here the spectrum of an LED varies dependent upon the lens?

Unless the lens employs a dichroic filter(which would be highly irregular) I find this hard to believe. The spectrum of an LED depends upon the type of semiconductor material and/or phosphor. The lens only determines the angle of focus.

My understanding is that the red light is mostly filtered out in the first 10 meters or so. This is consitant with my very limited diving experience. I'll eat my virtual hat if I'm wrong on this.

You are correct in that my use of the word lens was inaccurately portrayed. Main point was that LED's have potential to offer almost anywhere on the spectrum, but the technology involved limits the final variability of spectrum produced.

And yes, the majority of the higher [nm] spectrum is filtered out before the rest of the spectrum as relating to water depth. And there are a number of corals that have evolved to rely more on the lower peaks of spectrum - however those lower peaks still are much higher than "pure Actinic" light. Add to that, said corals will naturally rely more on [less productive] chlorophyll B over [more productive] chlorophyll A...leading to slower growth rates [both as a species and an individual].


Thats the science, problem comes in when we involve the intricacies of our hobby's lights...

"True Actinic" is around that 420-460 nm peak we usually refer too. Actinic is Actinic - in scientific discipline that is.

However, the LEDS offer a very focused spectrum output with great peaks where they are needed but they do not produce the constant "background radiation spectrum" of a T5 or MH.

Ergo you would have better luck growing with only a T5 Actinic light than with only a LED Actinic Light in my opinion and experience.




But I just prefer to give my corals the maximum potential amount of light they can use. I'd rather 'fatten them up' as much as possible with light as they are then more colorful.

Just because a coral grew in deep water, and rely's more on the lower spectrum chlorophyll B [that still needs ~600nm] and it can "survive" on less light, doesn't mean that we can't expose these corals to slightly BETTER than normal conditions in hopes to produce a more photosynthetic reliant [more colorful] next generation in reproduction.


Even if it's 10 years down the line as I hope to keep my tank going

I understand the corals "look better" under more Actinic light, they glow like nothin! However, they require more [higher spectrum] light than that to reach their full potential.

How close you want to get them to full potential is your choice




And just to throw a monkey wrench in the 'light depth and red light' situation....

You do realize there are 2 tides a day, exposing the corals to a variable depth in water throughout the day...

And those tides are more powerful [in water level added/removed] toward the equatorial / tropical belt where our corals typically grow...

http://www.math.nus.edu.sg/aslaksen/teaching/tides.html

So the corals are very possibly [at least for periods] getting more Red light than you'd assume at first glance..

 

[ac0go]

I use one purple plus in my 4 bulb setup and never noticed any more algae growth when I switched.

 

[yardboy]

A few things I like to keep in mind when trying to determine what spectrum and intensity of light my corals need and that is pleasing to my eye:
1) the shorter the wavelength, the more energy available for work.
2) chlorophyll a and b have two absorption peaks, in the 400nm range and the 600nm range.
3) corals evolutionary advantage over algae is that the coral can produce fluoresent proteins that absorb higher energy light which is not so readily absorbed by water and retransmit it at the longer wavelengths utilized by the chlorophyll, so favoring higher Kelvin bulbs tends to favor coral over algae.
4) Some corals, and corraline algae, have pigments that reflect red light. Since the higher Kelvin bulbs have much lower levels of red light to be reflected, these corals do not look as attractive in an aquarium so adding bulbs with some red light will make these corals look better.
5) excess nutrients give algae an edge over corals, so keeping them low is more important than adding a bit of red light to enhance red pigments in corals.

And just to throw a monkey wrench in the 'light depth and red light' situation....

You do realize there are 2 tides a day, exposing the corals to a variable depth in water throughout the day...

And those tides are more powerful [in water level added/removed] toward the equatorial / tropical belt where our corals typically grow...

http://www.math.nus.edu.sg/aslaksen/teaching/tides.html

So the corals are very possibly [at least for periods] getting more Red light than you'd assume at first glance..

A gross simplification of the causes of tides on earth.
My experiences include only one tide a day in the Gulf of Mexico,
at latitude 49, tides of 50 feet, far above where corals exist
latitude 9, tides of 2 feet, at a center of coral diversity (more species of corals than anywhere else)

 

[tomservo]

However, the LEDS offer a very focused spectrum output with great peaks where they are needed but they do not produce the constant "background radiation spectrum" of a T5 or MH.

But MH spectrum graphs are spiky all over the place.. IE http://www.advancedaquarist.com/201...uamaxx_150w_de_all_ballasts.jpg/image_preview looks not too different from an LED setup with 420's, 450's and whites (1:1:1).. at least in the blue range, white LEDs take over for the rest and it's quite smooth.. http://www.1023world.net/diy/spectra/dl/eLFF.jpg generated with the 1023world spectrum chart tool.

In fact I'd dare to say the LED has a smoother spectrum than the MH.

 

[VectorAKA]

I remember reading in the tank of the month for June that Nano(however was spelled) got the best growth out of the 6500K lights....and the higher temp bulbs brougt out the best color.....

 

[JHawlz9989]

But MH spectrum graphs are spiky all over the place.. IE http://www.advancedaquarist.com/201...uamaxx_150w_de_all_ballasts.jpg/image_preview looks not too different from an LED setup with 420's, 450's and whites (1:1:1).. at least in the blue range, white LEDs take over for the rest and it's quite smooth.. http://www.1023world.net/diy/spectra/dl/eLFF.jpg generated with the 1023world spectrum chart tool.

In fact I'd dare to say the LED has a smoother spectrum than the MH.

Is the LED spectrum graph really representative of the spectrum? If each LED emits only a specific wavelength, how is it possible that any LED fixture would have a curved spectrum graph. You should see a spike at whatever wavelength is present, with nothing in between. Is that correct?

Josh

 

[tomservo]

The graph is correct - single color LEDs emit a spectrum that peaks at a specific wavelength, but it's more like a parabola. Usually there is significant output (60-80% intensity) at +- 10-20nm from the wavelength peak. Some LEDs are "tighter" than others in this regard, but none have spectral peaks like you get in MH and some fluoros, where there is a massive spike at a single wavelength.

White LEDs have a smooth spectrum, and usually a largish parabolic spike around 455 blue, which is light directly from the emitter that leaks through the phosphor. Hence, higher kelvin emitters "simply" use less phosphor, and higher lumen efficiency emitters use more green phosphor and less red/cyan/orange.

 

[ReeferBatman]

Ok, so going for natural sunlight Par Curve



and realizing there are other fluorescent pigments at nanometers below my LED or T5 Actinics offerings... I now got some extra low UV's with my blacklight

I now have 4 different lights on my tank... In 'timed' overlapping order...

1 T? Blacklight (from College days... )
~22w Blue Actinic
T5 = 54w 10k / 54 w Actinic
(another) T5 = 54w 10k / 54 w Actinic

Here are the pics... the Blacklight first brings out tons of reds and oranges!

Then Actinic LED's... Note the more intense greens!

Then LED + 110w T5

Then LED + 220w T5

PS...

Check out my 8 inch long Brain Coral under only UV Blacklight!!

For reference of spectrum's needed, see...

http://www.youtube.com/watch?v=g3vdfkqOLtU

http://www.advancedaquarist.com/2006/9/aafeature

 

[Crit21]

@ReeferBatman,

You should do more research into photosynthesis. The first diagram you reference is from a non-scientific source. The diagram from saltaquarium.About.com is actually using a photosynthetic chart for plants. Coral photosynthesis is much different. Corals live in a blue-dominated environment.

• Coral growth rate is better when the amount of blue light is increased, but coral growth rate decreases when the levels of red light are increased, even when accompanied by an increase in Kelvin rating: www.advancedaquarist.com/2008/12/aafeature1
• Pay particular attention to the paragraph titled, "The Red Light Theory Revisited."
• Red light can cause coral bleaching: www.advancedaquarist.com/2003/11/aafeature
• Corals have blue light-sensing photoreceptors that cue coral branching toward the blue light source, which is the dominant light in the coral environment. There is no corresponding red photoreceptor in corals: http://jeb.biologists.org/content/212/5/662.full.pdf
• The chart titled Excitation Wavelengths of a Pigment found in a Pink Acropora Specimen is not related to photosynthesis at all. To the contrary, it refers to fluorescent pigment excitation wavelengths. Excitation and the resulting fluorescence is a defensive mechanism corals developed to protect against harmful wavelengths and excess absorbed energy that would otherwise damage the photosynthetic mechanism.
• Photosynthetic corals exist in the photic zone or euphotic zone zone of the ocean (the depth at which organisms are capable of utilizing carbon dioxide in the presence of light as a source of metabolic carbon), which extends to approximately 100 meters depth, not 100 feet.
  Light is absorbed by water at varying rates depending on wavelength and water clarity
• Almost 60% of red light (700nm) is absorbed in the first meter of water, and >99% is absorbed by 10m depth. By comparison, only 2-3% of sunlight between 400 and 500nm is absorbed in the first meter of water, and only 15-25% is absorbed by 10m.
  
  There is a clear and significant relationship between colony depth (3m and 40m) and photosynthetic performance under blue light spectra (http://jeb.biologists.org/content/213/23/4084.full)
  - Deep water corals had higher photosynthetic performance when they were exposed to blue light in comparison to full PAR illumination under the same light intensities.
  - Shallow-water corals showed the opposite response, with higher photosynthetic performances under full-spectrum PAR than under the blue light (same irradiance).
  - Conclusion: Unless the coral originates from very shallow water (naturally or aquacultured), the corals will respond best to blue light.

 

[Crit21]

And to those interested, it does get even more complicated with different spectrums needed for both types of chlorophyll in the corals/plants...

Chlorophyll B is where the coral gets more of its energy (more from the blue/green spectrum too) but Chlorophyll A is the 'good stuff' that the coral really wants... in addition B will increase the capacity to intake/utilize A.

Think of it like I said before, the lower spectrum 'preps' the coral to take more advantage of the higher spectrum offered.

If you were only offering 600-700nm light, the coral could not fully photosynthesize even though that's the most needed part of the spectrum.

Note that even though it really really needs that upper spectrum to fully produce food, the majority of light absorbed is still in that blue/green spectrum - leading to those colors we love in our corals.



So no - offering the full spectrum to the coral will not promote red zoo-x over blue/green coloring in the corals. It may bring out some more colors in the coral, but it will not replace the blue/green coloration.

 

[Crit21]

And to those interested, it does get even more complicated with different spectrums needed for both types of chlorophyll in the corals/plants...

Chlorophyll B is where the coral gets more of its energy (more from the blue/green spectrum too) but Chlorophyll A is the 'good stuff' that the coral really wants... in addition B will increase the capacity to intake/utilize A.
Think of it like I said before, the lower spectrum 'preps' the coral to take more advantage of the higher spectrum offered.
If you were only offering 600-700nm light, the coral could not fully photosynthesize even though that's the most needed part of the spectrum.
Note that even though it really really needs that upper spectrum to fully produce food, the majority of light absorbed is still in that blue/green spectrum - leading to those colors we love in our corals.
So no - offering the full spectrum to the coral will not promote red zoo-x over blue/green coloring in the corals. It may bring out some more colors in the coral, but it will not replace the blue/green coloration.

This is completely inaccurate relative to corals. First, corals do not use chlorophyll b. As one scientific paper put it, "chlorophyll b is not measured because it is indistinguishable from that found in the filamentous algae that is present in corals. In other words, chlorophyll b is not a factor in coral photosynthesis. Keep in mind that corals are in a red-deficient environment. Photosynthesis in corals evolved/developed to take advantage of the high energy blue wavelengths. If you look at the photosynthetic apparatus in corals you'll find that every molecule and protein takes advantage of wavelengths between 400nm (violet) and 500nm (blue). This includes chlorophylls a and c2, the carotenoids (diadinoxanthin, diatoxanthin, and beta carotene). Beta-carotene, peridinin and xanthrophylls are also antenna pigments, and the perindin-chlorophyl a-protein (PCP). The carotenoids help to collect light wavelengths which are not absorbed by chlorophyll itself, then pass their absorbed energy to chlorophyll. The perindin-chlorophyl a-protein (PCP) is a light-harvesting complex that uses perindin as its main light-harvester. Xanthrophylls also absorb excessive energy that chlorophyll cannot use, dissipating that unused energy so that the photosynthetic apparatus is not damaged.

 

[Crit21]

LED's offer the entire spectrum - HOWEVER the actual spectrum they give out is entirely dependent on their lenses. Hence one LED light will perform miraculously, while another LED is pure $hit.

Sounds like your missing your upper spectrum, and the Zoo-x is ejecting from the coral in hopes of better territory [more light] somewhere else.

Throw some higher spectrum on there.

Your whites (5000-8500) are in the right spectrum to promote regular [above ground and freshwater] plant photosynthesis, not coral photosynthesis. Replace those with something higher (in Kelvin / nm) like 10,000k t5 or more specified LEDs.


I supplement my 10,000k t5's with LED actinic Blue's for example.

As to your confusion - its easy as light has no real easy to relate measurements...

Kelvin - is color to our eyes.
Nanometers - is the spectrum of energy delivered.
Watts - are merely a human energy consumption measurement - unrelated to
Intensity - amount of energy delivered.

Par value is an attempt to 'morph' all of these into one easily representable graph, but then it doesn't represent every aspect as well... but its the best for our purposes.

ReeferBatman, what is the source of the information you're presenting as fact? Either you misspoke or are incorrect.

Lenses have absolutely no effect on spectrum (the range of wavelengths emitted by the light source). A cool white LED will emit the same spectrum through a lens as it would without a lens. Their sole function is to focus light onto the desired area, thereby increasing intensity and the resulting PAR in a unit area.

cpandrewschmidt, you'll do just fine with the white, blue and royal blue. Any bleaching after switching to LEDs could easily be from too much blue light intensity. I found this out the hard way when switching a 150G from 2 400W 14,000K MH and 200W of actinic VHOs to just 240W of 3W white, blue and royal blue LEDs. I bleached some corals because I was providing too much light energy (shorter wavelengths have much higher energy levels). I'll try to be very brief in my explanation. Essentially, blue/violet wavelengths (410-500nm) result in a higher photosynthetic response than any other wavelength. Depending on the wavelength, you can increase the rate of photosynthesis by a factor of 2 or 3 times over other wavelengths or even warmer white light. If you're using blue LEDs, you need to find a way to dim them almost completely until the zooxanthellae acclimate. You can do this in one of several ways: dim the blues and turn them up gradually over 2-3 weeks, use screening to cut the exposure level, increase the distance between the LEDs and the corals temporarily, or remove any lenses to reduce the intensity of light that reaches the corals.

What a lot of LED users find is that their tank look less bright when viewing. This is because the blue LEDs don't provide the visual aesthetics that whiter light sources provide. The thing to remember is that you need to strike a balance between aesthetics and coral health. You can get great health with LEDs using LEDs that emit between 410-500nm (the dominant spectrum below 10 feet); however, you'll hate the visual appearance. You'll get good visual appearance with cool whites, but much slower growth.

The lack of red light has nothing to do with red corals. Those corals are red because they reflect red wavelengths, meaning they do not absorb red light.

As far as adding violet, while it will cause additional pigments to fluoresce, it's not going to increase growth noticeably. It's also much harder for the human eye to see violet light, and the violet-emmitting LEDs don't have a high intensity.

 

[Crit21]

I've been reading articles on advanced aquarist and their experiments on light and coral growth.

There's one study from 2008 that shows growth of hard corals correlated worse with increasing red light. And didn't correlate with more blue. 10K bulbs actually did the worse in terms of growth rate and their percentage of red light was the greatest.
http://www.advancedaquarist.com/2008/12/aafeature1


There's another one from 2003 that shows bleaching and poor growth of sps coral with narrow spectrum red led.
http://www.advancedaquarist.com/2003/11/aafeature


This one shows the mitosis of zooxanthellae slows when more red light is added to the light spectrum.
http://www.advancedaquarist.com/2009/5/aafeature/

What I gather from these studies is that more red light inhibits coral growth even if temporarily. Bulbs with 10K actually correlate to the worst growth rate and bulbs 14K to 20K correlate to the best growth rate.

Take it for what that's worth. I've heard so much on these boards that using warmer white bulb helps with growth which is clearly not what these articles and experiments show.

Personally, I'm looking to replace my T5 bulbs with the higher K to see how the corals react and get rid of the reds and 10K's. It'll probably not look aesthetically pleasing, though...

JCW, you've got it right. Bulbs with higher Kelvin ratings will promote better coral growth with one caveat--higher levels of red slow the growth of the corals, independent of the blue light present. The 2008 study showed that, even though it had a higher Kelvin rating, the 10,000K bulb (with the highest red emissions) produced slower growth than the 5,500K, 14,000K, and 20000K bulbs. This would just have been an interesting note if not for studies by other researchers.

You don't have to get rid of your red lights (LEDs?) if you only have them on during viewing and if you only have a couple of them.

 

[jeremy K]

Interesting. So, if true, I would expect coral bleaching or slowed growth in a T5-lit tank that was heavy on the purple plus bulbs (high in red, albeit also high in blue). Interestingly, this is not what I have found in my tank where 3 out of my 6 bulbs are purple plus (I like how they make my tank look far better than I like the look of blue plus bulbs).

 

[Crit21]

I hope you read the studies in the links first. They'll actually answer your questions.

Bleaching? Only if you have too much light intensity and cause the zooxanthellae to leave the host. Slowed growth compared to a light source with less red light? Absolutely, especially when you use the KZ Fiji purple. It outputs a massive amount of red, which is a great stimulator of photosynthesis in plants. If you ever get any kind of green algae, the red supplementation from the KZ Fiji purple will help you grow a bumper crop.

You can put up Christmas lights if it makes you happy. It's your tank. I've been into saltwater aquariums for 20 almost years now, and I remember when it was considered axiomatic that 5,500K was the absolute best kind of lighting for corals because it was close to natural sunlight. Nowadays that's considered laughable. What no one seemed to consider was that corals live deeper in nature than they do in an aquarium. The vast majority of corals in nature live in an environment deprived of red, orange and yellow light.

 

[jeremy K]

Fair enough. But one piece of information is still missing from the equation, and that is coral coloration (as opposed to growth). Some of us actually wouldn't mind slower coral growth (less pruning necessary), but want the best colors for our own esthetic senses - after all, our tanks are mostly ornamental.

Now, I would hypothesize based on your information, that purple bulbs should cause browning of sps, due to zoox growth (they are algae, after all). Again, this is not what I have seen personally in my own tank, but then perhaps colors might be better without the red light? Then again, perhaps the red light might cause enough purging of zoox to improve coloration?

 

[JPMagyar]

Purple Bulbs.

Purple Bulbs.

Let's do a summary for anyone reading this thread so far:


OP's question: Purple bulbs effects on coral and algae?

Answer: Very good for corals and makes no difference for algae!










But,


Thank-you Crit21 for taking on the discussion ReeferBatman brought on regarding corals and light, and ReeferBatman I hope you are willing to take the criticism of your comments with the friendly intent it is given.



Here's how I understand the discussion:

ReeferBatman said corals need light in the 600+ nm spectrum to optimize growth and "actinic" light (420 nm) is not enough to grow coral without supplementation so he recommends bulbs with 10000 kelvin color rating to optimize coral growth.

The truth . . .


If you want a nice tank you do NOT need 10000k lighting. If you like the look of 10000k lighting then awesome, go for it, but again YOU DO NOT NEED 10000k lamps to "optimize" coral growth in a home reef.


Here are three tanks that use actinic and 20000k lighting, one of them is mine.

Here is ReeferBatman's tank:

They key here is "optimizing coral growth" for all coral types. It seems higly logical to me that optimal coral growth on an actual reef requires a broad spectrum of light, but it is most definitely NOT true with regards to the saltwater aquariums the vast majority of reefers on RC want to keep.



Lastly for those wanting the absolute latest information on this topic I suggest . . .

Aquarium Corals: Making Corals Colorful: New Information on Acropora species
by Dana Riddle

 

[jeremy K]

JPMagyar, your tank is stunning. But I must ask you - you say that you use 20K light plus actinics. Are you, by any chance, using MH lights, or are we talking T5. If you are talking 20K MH, that is a totally different ballgame, since those bulbs cover the entire spectrum of visible light and even UV, even though they are heavy in the 20K range. If, however, we are talking about blue plus T5 bulbs, these do NOT cover the entire spectrum, and hence the topic of discussion.

Also, your summary thus far at the top of purple bulbs - no effect on algae, good for corals - is still in dispute...hence the last few posts.

 

[Crit21]

Jeremy K, the red spike in the KZ Fiji purple appears to be at the right point to benefit plant growth. You might like the aesthetics, but in the long run, you risk promoting algae growth, particularly if you have phosphates and nitrates above the absolute minimums (algae scrubbers are gaining popularity as nutrient exporters in some circles).

Coloration and health aren't mutually exclusive. The photos above are representative of my point. When I switched to blue/royal blue and white LEDs not only did I get massive growth, but I got rapid growth and coloration (pigmentation) that I'd never experienced with MH or fluorescents. It doesn't matter whether you use T-5s, MH, LEDs or a combination. If you give the corals what they need to grow and be healthy, you're going to be happier. Of course, lighting can't overcome bad water parameters or flow issues.

Regarding the browning-out statement, browning is caused by insufficient light. The zooxanthellae multiply in order to gather more light.

Here's a pic of my ORA Red Planet and my Ultimate Milli after a couple months' exposure to my LEDs. They were very happy corals!

Here's my pocillopora meandrina after 2 months under the LEDs. Notice several dozen new growth nodules. It also turned from brown to a nice purpleish color.

 

[Crit21]

JPMagyar, you're correct. I was trying to educate, not slam. I don't know everything and never will, but nowadays I believe in using reputable sources and peer reviewed data instead of opinion and guesswork. I have too much to lose.

Dana Riddle has published several articles on AdvancedAquarist.com regarding coral coloration. I need to see if they add anything to the equation, but the biggest problem is that one spectrum does not satisfy all aquarium corals equally, since they come from a wide range of depths. Shallow water corals do a little better with a little more broad spectrum, while deeper water corals prefer blue/violet. That's why I compromise and prefer 20-25% white LED and the rest as a combination of 400-510nm.