What is the benefits of using 20k or actinic bulbs? Right now I have a 20k and a actinic 55watt pc bulb. I didnt realize that 20k != actinic because I am such a n00bie. Can anyone say why I would want the more purple or blue light?
Actinic vs 20k?
- Thread starter johnehr
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Curtswearing
Mantisfreak
Here's the deal. Everyone is always looking for the 'Best' light. There is no 'best' light. It is going to depend on what type of corals you want and what your goals are. PAR (intensity) is needed for good coral growth. 6500k Iwaki's are all that you need for good growth. Unfortunately, if you kept SPS, you would end up with a tank of brown sticks and the water would look yellow. The zoox would be in full control and would show through as brown. (BTW...if you have high Phosphates or Nitrates, your corals will also turn brown. The zoox will start using those as their food source and stop photosynthesis. If this condition is allowed to continue for too long, the coral will bleach on purpose to lower the numbers of zoox. I'm telling you this because sometimes people who keep SPS blame their brown corals on their lighting when in fact, they need to get their water cleaner).
Wavelength is needed for good coloration. Unfortunately, the higher you go in Kelvin (wavelength), the less PAR (or intensity) is put into the tank so the corals get less light. The manufacturers overcome this by usually only having high Kelvin MH's as 250 or 400 watt bulbs. If you put 20k Radiums in as a 175watt bulb, you would have highly colored corals that didn't grow and would probably start to decline.
Zoox is always brown but Corals also have color pigments. Fluorescent Pocilloporins and highly Flourescent Pocilloporins. The highly flourescent polilloporins absorb light in one spectrum and reflect it in another spectrum. Those are the puppies we like to manipulate with our different spectrums of bulbs.
The following spectrums were copied from this article Stoney Coral Pigments by Steve Tyree and this link that requires Adobe Acrobat.
Pocilloporin primarily absorbs green/yellow (550-600 nm) light along with some upper UV-A . it emmits a orange/red
UV fluorescing pocilloporins primarily absorbs light from 310 to 380 nm (UV-B and UV-A) and then fluoresces this as light from 400 to 470 nm (violet/blue).
Violet fluorescing pocilloporin primarily absorbs light from 380 to 470 nm (UV-A, violet and blue) and fluoresces light from 475 to 520 nm (blue and green).
Blue fluorescing pocilloporin primarily absorbs light from 430 to 490 nm (violet and blue) and fluoresces light from 490 to 540 nm (green/yellow).
Yellow fluorescing pocilloporin primarily absorbs light from 440 to 500 nm (blue) and fluoresces light from 520 to 620 nm (green, yellow and orange).
Red/Orange Fluorescing pocilloporin that primarily absorbs light from 500 to 540 nm (green) and fluoresces light with wavelengths that are primarily orange to red.
Corals can have more than one pocilloporin in them so you can often change their colors simply by changing the wavelength you put them under. Japanese reefers do this by putting specific corals under specific bulbs.
If you are keeping toadstools, colts, and other similar brown corals, none of this matters because they don't fluoresce anyway. You would probably only want the actinics added to just to prevent the tank from looking yellow to your eyes.
Most True Actinics peak in the 420 nm range which affects Violet fluorescing pocilloporin. However, there is also some benefit to Blue fluorescing pocilloporin. Therefore, most actinic bulbs that peak around 420 will enhance blue and green and yellow. If you are keeping corals that flouresce, then having actinics can make your tank look better to our eyes but it doesn't really matter to the coral.
I would recommend that you read the thread called Lets talk about lighting because Mojoreef is much better at explaining this concept.
The above was from this article. It clearly shows why many corals like most of our reef corals and corals that live in shallower waters on patch reefs like lighting in the blue, indigo, and violet spectrum.
If you go look at the spectral analysis articles by Sanjay Joshi and Joe Burger in the library, then you can specifically pick a bulb that serves your needs.
Wavelength is needed for good coloration. Unfortunately, the higher you go in Kelvin (wavelength), the less PAR (or intensity) is put into the tank so the corals get less light. The manufacturers overcome this by usually only having high Kelvin MH's as 250 or 400 watt bulbs. If you put 20k Radiums in as a 175watt bulb, you would have highly colored corals that didn't grow and would probably start to decline.
Zoox is always brown but Corals also have color pigments. Fluorescent Pocilloporins and highly Flourescent Pocilloporins. The highly flourescent polilloporins absorb light in one spectrum and reflect it in another spectrum. Those are the puppies we like to manipulate with our different spectrums of bulbs.
The following spectrums were copied from this article Stoney Coral Pigments by Steve Tyree and this link that requires Adobe Acrobat.
Pocilloporin primarily absorbs green/yellow (550-600 nm) light along with some upper UV-A . it emmits a orange/red
UV fluorescing pocilloporins primarily absorbs light from 310 to 380 nm (UV-B and UV-A) and then fluoresces this as light from 400 to 470 nm (violet/blue).
Violet fluorescing pocilloporin primarily absorbs light from 380 to 470 nm (UV-A, violet and blue) and fluoresces light from 475 to 520 nm (blue and green).
Blue fluorescing pocilloporin primarily absorbs light from 430 to 490 nm (violet and blue) and fluoresces light from 490 to 540 nm (green/yellow).
Yellow fluorescing pocilloporin primarily absorbs light from 440 to 500 nm (blue) and fluoresces light from 520 to 620 nm (green, yellow and orange).
Red/Orange Fluorescing pocilloporin that primarily absorbs light from 500 to 540 nm (green) and fluoresces light with wavelengths that are primarily orange to red.
Corals can have more than one pocilloporin in them so you can often change their colors simply by changing the wavelength you put them under. Japanese reefers do this by putting specific corals under specific bulbs.
If you are keeping toadstools, colts, and other similar brown corals, none of this matters because they don't fluoresce anyway. You would probably only want the actinics added to just to prevent the tank from looking yellow to your eyes.
Most True Actinics peak in the 420 nm range which affects Violet fluorescing pocilloporin. However, there is also some benefit to Blue fluorescing pocilloporin. Therefore, most actinic bulbs that peak around 420 will enhance blue and green and yellow. If you are keeping corals that flouresce, then having actinics can make your tank look better to our eyes but it doesn't really matter to the coral.
I would recommend that you read the thread called Lets talk about lighting because Mojoreef is much better at explaining this concept.
The above was from this article. It clearly shows why many corals like most of our reef corals and corals that live in shallower waters on patch reefs like lighting in the blue, indigo, and violet spectrum.
If you go look at the spectral analysis articles by Sanjay Joshi and Joe Burger in the library, then you can specifically pick a bulb that serves your needs.
jlehigh
Hermit D Crab
Holy Pete! Nothing like summing up the 90hrs of reading and research I did into a i pager...
Beckmola24
Hawkfish
This thread has really helped me understand lighting better. I was able to find the PAR of my exact bulbs. I consider myself a more informed reefer now. You're awesome Curt! 
hansoloalaska
Member
Thank you Curt!! Learned alot from your post and have it printed for future refrence!!
Stang69
OFR!
Thanks for the info Curt you RAWK!
Jeff
Jeff
