Lighting type question

[Nu2SW]

OK so I got some power compacts and man are they BRGIHT, Its one half of the tube is 10,000K and the other half is Actinic,

Now the question i have is the Actinic lights. what do they do and what are they for. Im curious about them, never seem them before?

 

[Reefugee]

The actinic is a blue light. Blue light basically makes a lot of stuff in your tank fluoresce.

Minh

 

[Marc Daniels]

They are only for looks, as Minh mentiond. The PAR is pretty low on them so they don't help the coral that much. Really depends on the coral depth, wattage, etc. They have done studies, and if you mount them more than 3"-4" above the water the light (PAR) entering the water drops quite a bit due to air diffusion.

 

[Nu2SW]

total is 265 watts and its about 2 inchs above water.

Man talk about total difference in how the tank looks.

 

[Marc Daniels]

For water penetration, it isn't the total wattage that's as important as the individual bulb wattage. With PC's a good reflector is also important.

 

[Nu2SW]

Yeah it has a good reflector inside, But im sure i could rig it for a better type.

 

[H20Sidhe]

Minh & Marc are way more experienced in the field of reefkeeping than I. However there is some science here. White light is made up of all the colors of the rainbow, with red having the longest wavelength (lowest energy) and violet having the shortest (most energetic photons). When sunlight hits the surface of the water, after having passed through the atmosphere, some of the light is absorbed, some reflected, and some transmitted. Due to the structure of water molecules, blue is the wavelength that is least absorbed, and that which penetrates the deepest into the ocean. It is also why water looks blue. Blue light is what reef animals living at more than a couple of meters depth receive the highest abundance of in the wild. That is the science part.

So I had always thought that it should be healthier for the animals to receive in captivity similar light to what they get in the wild. If blue is just for looks, as Minh & Marc say, then maybe we only use it to get them to look more like they do in the wild.

I do know from the molecular structure of the chlorophyls (which is quite similar to hemoglobin) that there are certain wavelengths which are better at stimulating photosynthesis than others in terrestrial plants, green being the most reflected (least absorbed). But the red wavelengths just don't penetrate water to any degree at all, and the zooxanthellae do not all use green chlorophyl for their photosynthesis!

Sherie

 

[Marc Daniels]

Interesting theory...I've never seen anything reported regarding the blue light being beneficial to fish. Sort of like sunlight helping us with Vit A.

I would have to say that it probably doesn't do anything. There has not been any research done in regards to our fish, but I'm sure there has to have been extensive research done on food fish...especially as it relates to farming.

 

[pepe.king.prawn]

I thought sunlight helps with vitamin D synthesis in humans, hence the fortification of Vit. D in milk, OJ etc???

H20Sidhe: you said "zooxanthellae do not all use green chlorophyl for their photosynthesis!" What do you mean by this? I know of chlorophyll a, chlorophyll b and carotenoids providing energy and metabolites via photosynthesis, but isn't all chlorophyll "green" since it is omitted from its absorption specrtum? Perhaps you could elaborate on how zooxanthellae acomplish photosynthesis.

Nu2SW: I'd say whatever reflector is in your PC fixture is probably ok provided it's polished aluminum. At some point you may be able to move the fixture closer to the water to increase the effective light intensity as was aforementioned. Anyhow, looks good so far!

 

[Marc Daniels]

Tristan...hey, at least I got the fact that it was a letter right. It is D.

 

[pepe.king.prawn]

Heh, I had to double check, but ya it's D. I'm amazed by such intricacies of biology and the human body! I believe the whole idea of enriching milk with vitamin D stemmed from children in Oakland who developed rickets as a result of a vit. D defficiency from being indoors so much. I recently began working in the human nutrition department here at UCD which is really fascinating as well. Somewhere between science and my reef tank, I always have a desire to work with the chemicals produced naturally in corals. I know there's a lot of cancer research in this area. Perhaps there will be something left for me to do some research on should I desire a PhD, maybe even before then now that I have access to cutting edge analytical instruments.

 

[CaliforniaDreamer]

Pepe, I am no expert but I think you are correct that chlorophyll a, b, and c are all green. I think the confusion comes in because of as you said the carotenoids (which are brown to orange and yellow) also participate in the conversion of sunlight to food for the plant. I found this web page that describes this interaction. In addition, as this article points out, Phycobilins are involved in energy conversion and also will fluoresce which enhance the colors we see.

 

[Nu2SW]

Tristan thanks a bunch. It might not be the greatest , But im proud of it and soon "slowly" it will be looking like a reef tank.

I took out the crushed coral and put in sand and added some live sand to it.

Next thing on my list are power heads, then a cannister type filter to get rid of the bio wheels i have.

 

[pepe.king.prawn]

Cool, thanks for the link! I suppose zooxanthellae do contain chlorophyll C then, since they are a dinoflagellate.

Despite this, is all photosynthesis made the same? That is to say, do zooxanthellae (and subsequently the chlorophyll & pigments contained within them) photosynthesize the same as the chrysanthemums growing on my window sill?

 

[pepe.king.prawn]

Sounds good. I just got a Seio 2600 recently and think it's awesome. If you're thinking you might want to keep SPS, I'd say give the Seio pumps a thought. A canister filter is fine, and I'd probably use one as opposed to using external overflows to allow you to use a sump. Only problem with canisters for me is that I never feel like cleaning them! haha. filter pads or socks in a sump are a breeze to clean/change.

 

[Wee-Reef Master]

Nu2SW,

In case it hadn't been mentioned, there are 2 forms of actinic. Traditional actinic (@7100K) and true actinic (03). The former is clearly brighter with a much higher PAR value. The latter is much like a black light that really makes your animals fluoresce, but has very little PAR value. I much prefer the traditional actinic for its brightness and appearance. Just my taste.

 

[CaliforniaDreamer]

I finally found this article that implies (if I understand the article correctly) that blue shifted light is just as good at photosynthesis as 10,000K light at the same PAR values. Of course the key is "at the same PAR valuesââ"šÂ¬Ã‚. I don't think that 15,000K or 20,000K lamps put out as many total photons as 10,000K lamps, but of this I am not sure. From the article and Figure 1. (An "Action Spectrum" for zooxanthellae) it would seem that blue light actually provides more energy for photosynthesis than longer wave length light. However when I read the article it said they used a PAR meter to read light levels which automatically adjusts to how well the light aids in photosynthesis. This would seem to invalidate their findings. It would seem that if they used a plain LUX meter the findings would have been more meaningful. In any case I found the article informative and somewhat helpful in that they also imply that the selection of lamp color does not have a major impact on photosynthesis of zooxanthellae.

-- EDIT --

BTW I believe that our eyes are not very good at determining light intensity. In addition my understanding is that we are somewhat poorer at detecting blue light.