John Pavao

I'm in a friendly argument with a buddy of mine who says that the only benefit of actinic light is for the viewer. I think it helps the photosynthetic life in the tank. Any input?

Luis Wiedemann

It is my opinion (which doesn't say much) that actinic lighting is for aesthetic only. I have more than plenty of light coming from my 65k 400w MH without actinics. I also think that there have been studies that prove that actinic lighting doesn't do much but I can maybe see how it can benefit deeper water species, IE..euphylia, favia, favites etc....

Eric Borneman

That's a crock. Now, if you have a tank that is mostly lit by metal halides and there are a couple of normal output actinics, it may be relatively small by comaprison. But if you have a tank lit by normal output lights, its a different story. If you use VHO actinics, its a different story. Actinic lighting is a special spectrum, sure - yes, its aesthetic, but it is also functional...as functional as any light soruce for corals and the spectrum part, while duplicating deeper water spectrum, is also functional to shallow water photosnthetic life.

Kevin McDonald

I'd have to disagree. While I don't have any documentation to prove it, someone here sure has the info handy... at any rate, I know there are different strains of chlorophyl, and some of them react differently to different wavelengths of light... some in the red spectrum, some in the blue. Zooanthelae no doubt have to be analagous. The photon's emitted in the "Actinic" Spectrum have higher energy. While some of the zooanthelae may not be able to utilize all the energy in the photon, I remember something vaugley from High School Bio class about chlorophyll being able to utilize a single photon multiple times in it's energy cycle (man, has it been a while since I studied any of that).

Dallas Warren

I think here you need to be all talking on the same level, which I don't think you are all currently.

The context with which I believe the statement that actinics are for nothing more than aesthetics is that it isn't that important what the composition of the spectrum of the bulb is, as long as there is enough light of the appropriate wavelengths for photosynthesis to occur. So as long as you satisfy the needs of photosynthesis, beyond that it doesn't matter what bulbs you use, actinic, day light etc.

As for Eric's stance on this, he is saying that the spectrum from actinic lights are important, because of the fact it is important for photosynthesis. So on this basis saying actinic lights is for aesthetics is incorrect, it can be very important if it is the important/dominant source of light of the right spectrum for photosynthesis to occur. So before anyone argues any further, may I suggest you state first on which part you are arguing ;-)

As to the original question, and as Eric has pointed out, whether actinics is important depends on how the tank is set up and the amount of light that the actinics contribute to the total photosynthetic available radiation. For example if you are running a 250W 6,000K MH with 40W of NO, then the NO contribution to the PAR is pretty insignificant and whether you use actinic or daylight is of no real consequence to the photosynthetic organisms in the tank. But your choice of NO will make a difference in how the tank appears to the human eye. Now what happens when you turn around and are just running NO or VHO over a tank? Half daylight and half actinic, are the actinics now there just for the look of the tank? Of course not, now it is making up a significant amount of the PAR.

Nick Jones

I'm certainly no expert, however I would like to agree with Dallas in his point of ratio's of actinics to other light sources used.

I currently use NO flourescents, 3 x 9,500K tubes and 2 x blue Actinics. I don't keep particularly difficult species, however the ones I do have are thriving including several species of sps.

I have noticed however that if I switch off the actinics during the day for several hours the majority of my corals will behave in a very odd manner. The mushrooms fold themselves into the most bizzare shapes, my bubble deflates to about one fifth of it's normal size and my sinularia's contract their polyps.

Once the actinics are switched back on, the corals all return to their former expansion over the period of about two hours. Also I have had a timer fail in the past, when I noticed the actinics weren't on, I looked in the tank closely I noticed that most of the corals in the tank looked as if they had failed to expand properly.

Personnaly I'm not sure if they are essential, however if your animals have adapted to them, they have a noticale effect if not used. (I assume until your animals adapt to other light sources) Just my 2 penneth worth :-)

Kevin McDonald

I think here you need to be all talking on the same level, which I don't think you are all currently.

WHAT?! Try and Clarify the topic... Ooooh, I'll get you for that ;-)

The context with which I believe the statement that actinics are for nothing more than aesthetics is that it isn't that important what the composition of the spectrum of the bulb is, as long as there is enough light of the appropriate wavelengths for photosynthesis to occur. So as long as you satisfy the needs of photosynthesis, beyond that it doesn't matter what bulbs you use, actinic, day light etc.

Yes, I see what you're getting at, and yes, this is an important distinction, and on a certain level, I can agree with the above statement. The purpose of our extravagant and expensive lighting systems is to provide energy for the photosynthetic critters in our care... To that I agree, and if you've got natural sunlight and an incandescent bulb and that fully meets your critter's requirements, actinic lighting would provide no greater benefit other than for the observer.

As for Eric's stance on this, he is saying that the spectrum from actinic lights are important, because of the fact it is important for photosynthesis. So on this basis saying actinic lights is for aesthetics is incorrect, it can be very important if it is the important/dominant source of light of the right spectrum for photosynthesis to occur.

Yes, this is what I was trying to say (there's this damn chart stuck in my head from 9th grade bio...) Without really showing my ignorance, in all of it's glory, I'll try to explain... Any of the biologists on the list can feel free to jump in here with some intelligent information any time....

As the chlorpophyll cells capture the energy from the photon, they basically steal some energy off an electron, and then let the light be on it's way. They use that energy to bond carbon and water or something, forming simple sugars, and pow, we've got photosynthesis. Higher energy wavelengths of light (e.g. Actinic spectrum), carry higher energy electrons, and the chlorpophyll is able to utilize a single electron multiple times to create it's sugars... It's like the energy cycle carried out in the mitochondria in our cells creating ATP, only in reverse (literally, almost identical to a T ). You'll have to forgive that horrid description, but it's been a few years since I studied any of this, and I've smoked a lot of dope in that time...

My POV stems from this concept (flawed as it's recollection may be... there never is a good biologist around when you need one?), and that in terrestrial plants, chlorophyll is able to use the increased energy contained in higher energy light. What I believe is that Zooanthelea are closely enough related to chlorophyll, that I believe they too may be able to make better use of higher energy lighting... e.g. actinics. So you can see why I say it's more than just aesthetics... I believe that the photosynthesis can be carried out at greater efficiencies using higher energy wavelengths of light, than using lower energy wavelengths. Of course I can't prove it... but I got some good theories kicking around in my head. There are two other things that keep gnawing away at this in the back of my head, and ironically enough it goes back to the terrestrial plants studied in my biology class...

1- There are different strains of Chlorophyll... there are also diff. strains of zooanthelae... each strain utilizes light differently. So matching up a light source to the active ingredient in photosynthesis I believe to be important to the effeciency of the overall equation.

2- At the depths most of these corals are collected at, isn't it really blue down there? Not to sound stupid, but the red and yellow wavelengths of light don't penetrate more than a few meters of saltwater, right... so the photosynthetic organisms are used to seeing and living in blue light, they are "adapted" to that environ. I make an analogy to where I work at a Printing Company... Our Printing Plates are light sensitive, so we have to put special yellow colored lights in everywhere in the plate room. After a 12 hour shift of fumbling around with the my Creo in there... you get used to the yellow lights. You start to perceive color's normally under the yellow illumination (your brain tells you what color you're supposed to see, it compensates for the light source). You get adapted to the environ. Over time, you will lose some color perception as your cones become adapted to viewing in those conditions. This can be observed when you go into a room with bright white lights. I'm no longer able to make color judgements on press, unless I've been out under their lights for at least 30 minutes.

I argue that over time, certainly when that time spans several generations, an organism will become so adapted and so specialized to it's environment (in the case of the corals we talk about), that they would only be able to effeciently use light from a given spectrum. One could argue that a photon is a photon, and the zooanthelae don't give a rat's you-know-what what color or wavelength it is, but I don't think so. Since I don't have the knowledge or documentation to back it up, I'll just stop there.

So before anyone argues any further, may I suggest you state first on which part you are arguing ;-)

I agree, this appears to be going into a two-part discussion, but I think the two parts are distinctively linked.

As to the original question, and as Eric has pointed out, whether actinics is important depends on how the tank is set up and the amount of light that the actinics contribute to the total photosynthetic available radiation. For example if you are running a 250W 6,000K MH with 40W of NO, then the NO contribution to the PAR is pretty insignificant and whether you use actinic or daylight is of no real consequence to the photosynthetic organisms in the tank. But your choice of NO will make a difference in how the tank appears to the human eye. Now what happens when you turn around and are just running NO or VHO over a tank? Half daylight and half actinic, are the actinics now there just for the look of the tank? Of course not, now it is making up a significant amount of the PAR.

I agree with what you're saying, when comparing a ratio of amounts of light measured in PAR. But what I'm trying to get across (and apparently not doing a very good job of it ;-), is that I believe different strains of zooanthelae are able to synthesize simple sugars more efficiently with higher energy wavelengths of light.

Whew... why couldn't I just say that the first time?

John Pavao

Thanks for all the input! I see my buddy and I aren't the only ones arguing about it, haha. My argument was the depth one.

My live rock is from Tampa Bay Saltwater, which means that it was farmed in the Gulf. The company states that the rock is "grown" at a depth of 20ft. I have the same rock in two tanks. One is a 29g with a 175w 5500K metal halide for lighting. The other is a 90g with 2 NO actinics and 2 NO plain lamps you would buy in a department store (yes, I will replace them when I can).

In the 29, the live rock looks "blasted". There is nothing on it but a few growths of macroalgae of different sorts. I can understand why there is no coralline, but everything else is gone too.

In the 90, it has life all over it, plus wonderful coralline algae. Both tanks receive Natureef two-part additive and the occasional kalk made from Mrs. Bell's Pickling Lime.

It's possible that the intensity of the light is part of it, but it was my understanding that 175w was great for a tank that size. (Interestingly, I had one NO and one actinic on that tank before the halide and the tank looked great until I added the halide and removed the fluorescents. The macros came out full blast under the halide and everything else croaked.

Eric Borneman

Thanks, Dallas, for nicely summarizing my point...thats exactly what I was saying...and naturally you would know the same as true ;-)

Kevin, you can disagree if you want, but I promise this is not a defended opinion. I can assure you I have the "data", and we can chat about relative contribution of wavelengths to zooxanthellae day and night - and I will have the papers to back myself up.

But, this is not the point. The point is if actinics are mostly aesthetic. They aren't. Photosynthesizers need light. They need x amount of light to reach their photosynthetic saturation level. Any above that must be dissipated or it is photoinhibitive or damaging. White light, red light, blue light....just get the photosynthetic machinery to that level. Now do corals have the photosynthetic machinery to do this with actinics. Yes. Case closed.

Now, if we want to talk about relative usefullness of various spectra and how the PCP complex and various types (not strains) of chlorphyll react in accordance with saturating and subsaturating light of various wavelenghts, we can. We will also see that white and blue light are MOST beneficial to stimulating zooxanthellae and providing corals with energy. Neat thing about actinics, on top of that, if their use in stimulating fluorescing proteins in corals, and this can be very important especially in low-light environments when UV and blue may be the only light waves to reach them.

It's possible that the intensity of the light is part of it, but it was my understanding that 175w was great for a tank that size.

The watts per tank size is a useless designation.

Again, referring to saturation points....if a coral, for example, requires 15,000 lux to saturate, it needs to get that amount of light regardless of tank size. So, if a 175 watt metal halide puts out 17,500 lux at the water surface and 8,000 lux ten inches down, its enough light for the coral at the surface but not at the bottom. The coral at the bottom will need to make up its carbon energy budget by feeding or absorption. Doesn't matter if the tank is 10 gallons or 10,000 gallons, see?

John Pavao

Got it. I'm afraid I never got into the technicalities that far. Do you actually measure the light like that to decide where to put the corals?

James Wiseman

If you're hammerina a 2'x2' area with a 400w iwasaki...I think that 40w of actinic is probably negligable...therefore aesthetic...;-)

Eric Borneman

Any of the biologists on the list can feel free to jump in here with some intelligent information any time....

I'm trying, but you aren't listening ;-) If you want some good reading material on the subject, let me know and I'll compile a list for you. Nice to see someone thinking about this and having logical arguments based on biology but not not having read the literature.

What I believe is that Zooanthelea are closely enough related to chlorophyll, that I believe they too may be able to make better use of higher energy lighting... e.g. actinics.

Zooxanthellae are algae. Chlorphyll is a molecule found in the chloroplasts of photosynthetic cells. Zooaxanthellae have chlorophyll a, c2 and an important goup called the peridinin- chlorophyll complex that allows them to utilize virtually all of the spectrum. The animal also has numerous types of nearby fluroescing proteins, below or above the zooxanthellae, to shield or a mplify excess or low light, including UV.

At the depths most of these corals are collected at, isn't it really blue down there?

Actually, no. Most aquarium corals are typically collected without scuba and from shallow areas...

Not to sound stupid, but the red and yellow wavelengths of light don't penetrate more than a few meters of saltwater, right... so the photosynthetic organisms are used to seeing and living in blue light, they are "adapted" to that environ.

Well, yellow goes to 45-60 feet, so that's pretty deep already. You'll lose most of the zooxanthellate corals at 150 feet, and no one is collecting that deep. In fact, i don't think anyone's collecting corals at 60 feet.

I agree with what you're saying, when comparing a ratio of amounts of light measured in PAR. But what I'm trying to get across (and apparently not doing a very good job of it ;-), is that I believe different strains of zooanthelae are able to synthesize simple sugars more efficiently with higher energy wavelengths of light. Whew... why couldn't I just say that the first time?

LOL. You are right. Different strains of zooxanthellae are light adated to different irradiance levels and spectra. However, corals are very photoadaptive and photoacclimatory, able to utilize all of the visible spectrum, some of the UV specturm, and change zooxanthellae number and types, pigment types and numbers, size and number of photosynthetic units, and have the fluorescing protein bonus package.

The real question is what light environment they were adpated to upon colection and how great is their ecological range in terms of depth and turbidity.

If you're hammerina a 2'x2' area with a 400w iwasaki...I think that 40w of actinic is probably negligable...therefore aesthetic...;-)

That point was already made, James-o. Catch up , wouldya? Jees!!!! ;-) But, if as Dallas and I pointed out, you are hammering a tank with irradiance from fluorescents, not so. Also, as a point of trivia, the 400W MH has a significant "actinic" component.

Got it. I'm afraid I never got into the technicalities that far. Do you actually measure the light like that to decide where to put the corals?

You can too with a handy little lux meter - costs about the same as a metal halide bulb. useful forever, even when tanning on the beach for fun and amusement.

Yes, I know the light levels in my tank very well. As for the corals, you kind of have to know where they are from and about them and their range, growth form, color, length of time out of the water, etc all come into play deciding where to put them in that given light environment. Even then, its a best estimate. And as they grow, some reach through several light environments because of the steep attentuation of light from light bulbs in water.

Kevin McDonald

If you want some good reading material on the subject, let me know and I'll compile a list for you. Nice to see someone thinking about this and having logical arguments based on biology but not not having read the literature.

Thanks for the offer, as much as I'd like to, I have a stack of Solaris books that take precedence... Not fun learning something like that on your feet... Actually, I have a terrifically funny story about that, that happened today, but I think I've already embarassed myself enough for one day (whoops, I think I spoke too soon...)

Zooxanthellae are algae. Chlorphyll is a molecule found in the chloroplasts of photosynthetic cells. Zooaxanthellae have chlorophyll a, c2 and an important goup called the peridinin- chlorophyll complex that allows them to utilize virtually all of the spectrum. The animal also has numerous types of nearby fluroescing proteins, below or above the zooxanthellae, to shield or a mplify excess or low light, including UV.

OK, so at least I was on the right track... My train of thought was that Zooaxanthellae (spelling it right would prolly help ;-) in corals is analagous to Chlorophyll in terrestrial plants. Maybe not an Apples-to-apples comparison, but pretty close (for a non-scientific viewpoint/discussion). Since Zooaxanthellae have chlorophyll in them... They surely will behave like it :-) Making that distinction between a cell, and a component found in an organelle is certainly important, but for the sake of this argument, I don't think it that critical - we're discussing the activity that goes on, not the part of the organism it takes place in.

Well, yellow goes to 45-60 feet, so that's pretty deep already. You'll lose most of the zooxanthellate corals at 150 feet, and no one is collecting that deep. In fact, i don't think anyone's collecting corals at 60 feet.

Now this one throws me... If yellow light is penetrating to the depths of water where our corals are collected... why are the "Blue Bulbs" (10K, 12K, 20K, actinic, etc.) all the rage? I thought the theory on them was that the spectrum from these bulbs more closely simulates the light at the depths most corals are found. Friends of mine that are into reefing and go diving, tell me that their tanks w/ 10 and 12K's look a lot closer to what they see in the ocean, than the pair of 6500K Iwasaki's and pair VHO Actinic's I run on mine. The argument being, that Iwasaki's are heavy in the yellow, not as heavy in the Blue's (actually, if I remember correctly, the Iwasaki's give a very balanced spectrum, but I don't want to turn this into an Iwasaki/10K debate.) So the Higher Temp bulbs crank out the blue light, and less of the other colors (but that doesn't mean it's not there). But if at 60 feet (the deepest any of our corals will be collected at), you're still getting plenty of yellow light, why the push for 10 and 12K? Not that I'm implying you've stated a preference for them... What I don't understand, is if the yellow light goes that deep, why's everything look blue? (I'm sounding daft again, aren't I?) I realize this gets off topic from the post, but the logic just doesn't jive with what's going on with popular belief at the moment (or are the masses blindly following the marketing people again?)

LOL. You are right. Different strains of zooxanthellae are light adated to different irradiance levels and spectra. However, corals are very photoadaptive and photoacclimatory, able to utilize all of the visible spectrum, some of the UV specturm, and change zooxanthellae number and types, pigment types and numbers, size and number of photosynthetic units, and have the fluorescing protein bonus package.

Sure, I remember reading about that on the net somewhere, that just because a coral bleaches, doesn't mean it's dead. It's just expelling it's Zooaxanthellae. This most frequently happens because the coral (or more correctly, it's Zooaxanthelae) are not adapted to the spectrum it finds itself in. So the coral kicks them all out, in favor of strains that are better able to utilize the lighting present. Since the Zooaxanthellae contain different strains of chlorophyll, some are able to deal with more/less intense light better, and are favored by the coral when it expells the other one's because of a shock to it's environment. The surviving Zooaxanthellae are able to reproduce and propagate the coral tissue. Have I fallen off the rocker again, or are we still on the same planet?

The real question is what light environment they were adpated to upon colection and how great is their ecological range in terms of depth and turbidity.

Yes, in regards to it's ability to adapt to the change in lighting conditions.

Whew... did that one ever run off topic... Thanks for the Solid Info Eric, I knew someone with a brain trained in this stuff would be able to help clear the fog. Now who has a Computer Question, I need to make myself feel smart again :-). In all seriousness though, back to the original question: are actinics strictly for aesthetics?

I agree with your statement, that if the coral has all the light it needs at it's disposal, what color it is, is irrelevant. As you stated, corals are remarkably adaptable to all kinds of conditions. Put a 1000 watt Mercury Vapor lamp over your reef and watch it all grow. Real long and stringy no doubt, but the Coral will adapt and grow. But in regards to what I was trying to remember about Chlorophyll being able to more efficiently utilize higher energy wavelengths of light, wouldn't it make more sense, to use a High energy light source at a lower wattage (e.g. VHO actinics) than a lower energy light source at a higher wattage (e.g. Mercury Vapor, or for a really far out example... Incandescent)? The original question was "that the only benefit of actinic light is for the viewer."

Now to extend that argument, you have to define "Benefit". Rather than go into a really long debate about the energy crisis going on these days, "is the coral any better off" gets to the root of the question, I think. Which, brings us full circle back to your above statement: "However, corals are very photoadaptive and photoacclimatory, able to utilize all of the visible spectrum, some of the UV specturm, and change zooxanthellae number and types..."

So without knowing where the coral was collected, and what conditions it had previously adapted itself to there, we can pretty much guarantee that ANY light we place above our tanks, is going to be drastically different than whatever the coral was used to. Makes one hell of a case for places like Atlantis Aquatics, don't it?

MY GOD I need a beer... I don't think I've thought that much since college.

Eric Borneman

They surely will behave like it :-) Making that distinction between a cell, and a component found in an organelle is certainly important, but for the sake of this argument, I don't think it that critical - we're discussing the activity that goes on, not the part of the organism it takes place in.

Yes, they will. Except they have a few nice adaptation themselves and in symbiosis with the coral to give them a "spectral" edge over chlorphylls.

why are the "Blue Bulbs" (10K, 12K, 20K, actinic, etc.) all the rage?

Good question. marketing? But, remember, perhaps the reason they are popular may be individual opinion and also that perhaps "not" corals don't do as well. i.e. less problem algae or cyanobacteria?

I thought the theory on them was that the spectrum from these bulbs more closely simulates the light at the depths most corals are found.

So we're told by the manufacturers. Seems plausable...but then, I guess many think they can rub a cream on their thighs and remove cellulite, too ;-)

Friends of mine that are into reefing and go diving, tell me that their tanks w/ 10 and 12K's look a lot closer to what they see in the ocean, than the pair of 6500K Iwasaki's and pair VHO Actinic's I run on mine.

Yes, but several things:

1) they are diving - and diving is usually deeper than collection.

2) the human eye is a bad judge of color underwater. We also bleed green at 60 feet. Literally.

3) water clarity affects this...yellows may disappear sooner in less clear water, etc.

4) the visible spectra as one goes deeper is made of proportionally more and more blue, even though actually its less and less of everything. Thus, it appears bluer.

So the Higher Temp bulbs crank out the blue light, and less of the other colors (but that doesn't mean it's not there).?

I think if you look at Richard Harker, Sanjay Joshi, and Dana Riddle's work with bulbs, you'll find that the 6500 bulbs put out more of every wavelength, including blue.

(on zooxanthellae) Have I fallen off the rocker again, or are we still on the same planet?

Nope, that's close enough for army work.

Now who has a Computer Question, I need to make myself feel smart again :-). In all seriousness though, back to the original question: are actinics strictly for aesthetics?

There is no answer. It depends on the proportion of light they represent in the total. Most people I know run relatively small amounts of actinic vs their total light with metal halides....in that case, its still functional but mostly aesthetic. I have a tank lit with 4 VHO's - two white and 2 actinic...in this case, its more than aesthetic.

So without knowing where the coral was collected, and what conditions it had previously adapted itself to there, we can pretty much guarantee that ANY light we place above our tanks, is going to be drastically different than whatever the coral was used to. Makes one hell of a case for places like Atlantis Aquatics, don't it?

Thats a good summary. There's a chance that the collection point and the ideal ecological range of the coral in question and our tanks are almost the same...pretty low, probably, but possible. We need collection data to really provide the same light, and we need to know the range of the coral to provide adequate light.