[charlie]

OK, here's the deal. I run 20K radiums from 12:30 PM to 9PM. Do I really need to run my actinic lites during this period?

[Poseidon]

The way I understand it, NOPE. Actinics are mostly for our benefit, not the corals...

[Reefland]

I don't see any reason to; they aren't really adding anything in the way of usable light; well nothing compared to your halides anyway.

[charlie]

Next question, do any of you use just the actinics for the dawn-dusk lighting?

[NoSump]

Originally Posted by Poseidon

The way I understand it, NOPE. Actinics are mostly for our benefit, not the corals...

Poseidon:

That's very interesting - I was under the impression that the Actinics were an important part of a reef lighting strategy (and not purely cosmetic). I have a 4 light PC outlet (It came with 2 10Ks, and 2 Actinics. Down the road, if I have problems with insufficient lighting for corals, would it make sense to go with 3 10Ks, and one Actinic (or will the lighting appear unattractively bright).

Thanks,

Chuck

[charlie]

Originally Posted by NoSump

Poseidon:

That's very interesting - I was under the impression that the Actinics were an important part of a reef lighting strategy (and not purely cosmetic). I have a 4 light PC outlet (It came with 2 10Ks, and 2 Actinics. Down the road, if I have problems with insufficient lighting for corals, would it make sense to go with 3 10Ks, and one Actinic (or will the lighting appear unattractively bright).

Thanks,

Chuck

If I were you, I would leave them the way they are. With the radiums that I am running, there is already enuf blue for everybody.
Your actinics will play a part with the corals because I don't believe that the 10k PC will provide the right spike in the blue spectrum.

[Reefland]

Well, the blue actinics, when only flourescents are running, are pretty important to provide another end of the spectrum as well as for aesthetic value. When your running halides, the actinics are pretty much for aesthetics.

[charlie]

Got another question. The way I have the timers on my hoods set up, the fans come on when the actinics come on. Do you think that I can do without the fans until the metal halides come on? Would that cause damage to the vho actinics?

[NoSump]

Originally Posted by Reefland

Well, the blue actinics, when only flourescents are running, are pretty important to provide another end of the spectrum as well as for aesthetic value. When your running halides, the actinics are pretty much for aesthetics.

Scott & Charlie:

Sorry to jump in on the middle of a thread - Thank you for clarifying the difference between MH and PCs in terms of light spectrum.

Chuck

[Rp Marine]

Originally Posted by charlie

Got another question. The way I have the timers on my hoods set up, the fans come on when the actinics come on. Do you think that I can do without the fans until the metal halides come on? Would that cause damage to the vho actinics?

if the actinics lights don't change the temp. of the water than you can leave it off until the mh turn on. if if it create enough heat to change the temp.

i would leave it on when any light turn on.
is the fan blow directly at the vho?

[charlie]

It's a PFO hood. They don't blow directly at the actinics.There is one at each end. 1 in, 1 out! Thanx for the help!

[charlie]

Originally Posted by NoSump

Scott & Charlie:

Sorry to jump in on the middle of a thread - Thank you for clarifying the difference between MH and PCs in terms of light spectrum.

Chuck

Hey no problem. I think that's what this place is for!!!!

[Poseidon]

Guess I should have clarified my statement better.. Thanks Scott for jumping in there. Sorry NoSump if I caused some confusion. Halides provide a pretty complete spectrum, not like the flourescents.

[Horace]

Originally Posted by Poseidon

Guess I should have clarified my statement better.. Thanks Scott for jumping in there. Sorry NoSump if I caused some confusion. Halides provide a pretty complete spectrum, not like the flourescents.

It is my understanding that adding actinics to 14k or higher kelvin Halides is not really needed. The 20k are VERY blue and to add more actinics would likely make it overly blue. I doubt that adding actinics would provide any benefit other than the ability to turn them on an hour before the halides and off an hour after the halides. This gives you your dawn till dusk effect and seems to be preferred by a majority of reefers.

In fact that is why I am going with the setup I have now chosen. I am going with 10k or 14k 2x150w DE and 2x Actinics. I will be doing the dawn/dusk thing as well...20k are a tad too blue for me...I like more of the white look.

[charlie]

Thanx for all the input people. I've been without actinics during the day since Friday. There doesn't seem to be any ill effects, but I will keep my eye on things.

[Poseidon]

You may want to change out the actinics for white or maybe "actinic white" with the 20K bulbs if they seem to BLUE... That is the nice thing about VHO or PC the bulbs are cheap enough you can experiment.

[charlie]

Originally Posted by Poseidon

You may want to change out the actinics for white or maybe "actinic white" with the 20K bulbs if they seem to BLUE... That is the nice thing about VHO or PC the bulbs are cheap enough you can experiment.

That is what I changed from! I thought that the actinic white looked almost pink, so I went actinic from them. I'm gonna keep an eye on things this week and make a final decision then. This IS all an experiment, right??

[Ninong]

Originally Posted by charlie

OK, here's the deal. I run 20K radiums from 12:30 PM to 9PM. Do I really need to run my actinic lites during this period?

The answer depends on why you are asking the question.

Are the actinic fluorescents beneficial in and of themselves? Of course they are! They have only about one-third the total PAR of a similar wattage 10,000K fluorescent tube because they are not full spectrum lamps. Virtually all of their output is centered around either 420 nm or 450 nm (there are two different kinds of actinic lamps). This happens to be a very important photosynthetic action range for certain pigments.

Don't confuse aesthetics with function. Whether you need actinic fluorescents to supplement 20,000K radiums is a decision that is usually made based on your personal preference. Many people may find that 20,000K Radiums (actually "blau", because the manufacturer doesn't call them 20,000K) are blue enough for their taste without any actinic supplementation. That's a personal choice that has nothing to do with function. Some people find that 20,000K Radiums are too blue all by themselves and they add 10,000K or 6500K supplementation to make the appearance of their tank more pleasing to their eye.

The correct way to think about whether or not you need actinic supplementation from the angle of function is to ask yourself if you are providing sufficient intensity in the 420-450 nm range. If you are using 6500K Iwasaki metal halides, you already have a lot of blue in your lighting even though you can't see it. That's because those lamps have a lot of intensity in the yellow-green range, which is where our eyes are more sensitive. This also means that we will think that we need a lot of actinic supplementation if we are running those 6500K Iwasaki metal halides even though we don't. We need the actinics because it makes the appearance of the tank more aesthetically pleasing to our eyes.

The ideal lighting for a mixed reef aquarium would provide broad spectrum lighting with an added dose of blue. That's assuming you are trying to duplicate lighting conditions that are natural at a depth of 5-10 meters. If you want to duplicate natural lighting in the top one meter from the surface, you could get by with just 6000-6500K. If you want to duplicate natural lighting at depths greater than 30 meters, you would use only 20,000K with actinics.

However, to complicate matters even more, don't forget that the Kelvin ratings used by the manufacturers often have little to do with the actual output of their lamps. Some 14,000K lamps are much bluer than some 20,000K lamps. Some 6000K lamps are whiter than some 10,000K lamps. Iwaskai even makes a 150w medium base lamp that they advertise as 50,000K. It's not nearly as blue as the 14,000K lamps from other manufacturers and it is whiter than the 20,000K Radiums. Also, the 250w 20,000K Radiums appear much bluer than the 400w 20,000K Radiums.

We're not finished with the confusion yet. It is possible to light your aquarium with just about any combination of lighting you choose provided to have adequate intensity. It might be "better" to provide full spectrum lighting but you can get away with just about anything if you have enough of it. That's because corals are so adaptable. If you provide "x" units of PAR to your tank, it doesn't make too much difference whether it's all coming from 20,000K Radiums or from 6500K Iwasakis. If we switch this concept to fluorescent lighting, you might have eight "units" of PAR using two 10,000K tubes and two actinic tubes. If you replace one of the 10,000K tubes with a daylight tube, that might give you a total of nine "units" of PAR, since the daylight tube has a little more PAR than the 10,000K tube. On the other hand, if you were to replace the 10,000K tube with an actinic tube (giving you 3 actinics and 1 10,000K), you might have only six "units" of PAR. So... Applying this to other lighting, such as metal halides or metal halides in combination with fluorescents, ask yourself if you think you have "enough" total PAR right now. If not, add some more. Maybe you would want to add some more in the form of actinics (even though they are low in PAR) because that would boost an important pigment action range and make the appearance more pleasing to you at the same time. Maybe you would want to add some more in the form of 6500K or 10,000K because you are really too low on total PAR and you need the most bang for your buck.

Check out Reef Central's Tank of the Month for February. That guy is running two BLV 150w 10,000K HQI DE lamps with two Osram 24w "blue" PCs over a 160-gal tank. That's it.


Most of his SPS are placed in the top one-third of his tank. How does he get away with just two 150w metal halides over that size tank, especially one that is 27.5" tall? Well, for one thing, he's using a high quality double-end metal halide lamp that produces more PAR than many 250w metal halide lamps. Not all metal halide lamps are created equal. Dr. Sanjay Joshi's testing has shown that some metal halides lamps of the same wattage produce three times as much PAR as others. BTW, I'm using an Aqua-Medic fixture myself, but I have the one with two 250w 10,000K HQI DE lamps. My two 250w 10,000K HQI DE lamps produce as much PAR as two 400w 20,000K Radiums. Actually, the PAR numbers Sanjay reported for the Ushio/BLV 250w 10,000K HQI DE lamp are higher than what he reported for the 400w 20,000K Radiums but he didn't use a UV-absorbing glass filter with the DE lamp and that is required, so after you deduct about 12% from the 250w DE lamp, the numbers are closer. Unless of course you decide that you should use a UV-absorbing glass filter with ALL metal halides, which is what most people (Dana Riddle, for example) recommend. Then we're back to the 250w DEs having more net PAR than the 400w mogul base Radiums. There are a lot of new brands of metal halide lamps on the market now. Their PAR numbers vary considerably from brand to brand.

And this doesn't even begin to touch on all the variables that are involved once you consider the needs of specific corals and their natural range as compared to what they can tolerate or adapt to in captivity. For example, the same species of the genus Acropora may be found over a range that can vary by more than 30 meters (100') in nature. It may be more abundant at a certain depth but it is present over a wide range. It won't have the same morphology at 25 meters that it has at 5 meters and it won't have the same coloration, but it's still the same species.

The simple answer to the question of whether actinics are valuable or not is that they are valuable. They add PAR. They add it in a very narrow but very important range. They are not just for aesthetics even though that is the way they are viewed by many hobbyists. Whether you want some or not is up to you because you can go either way. You can light your tank with just 6000K or just 20,000K if you like. The corals will adapt. My own personal preference would be for full spectrum lighting (10,000K) with added actinic supplementation (which is what I'm running). I would like even more actinic supplementation than I have but that's another story.

[charlie]

Don't confuse aesthetics with function. Whether you need actinic fluorescents to supplement 20,000K radiums is a decision that is usually made based on your personal preference. Many people may find that 20,000K Radiums (actually "blau", because the manufacturer doesn't call them 20,000K) are blue enough for their taste without any actinic supplementation. That's a personal choice that has nothing to do with function. Some people find that 20,000K Radiums are too blue all by themselves and they add 10,000K or 6500K supplementation to make the appearance of their tank more pleasing to their eye.

Ninong,
A simple yes or no would have done quite well!!!
I am still using the VHO actinic for the dawn and dusk. Bottom line is I guess I might be getting a little cheap in my older days. I am trying to save a little power consumption. The radiums have a real good spike at about 450, which is what the vho's are at. I am not worried about coral growth either, I get plenty of that.
With 6 radiums on my 300, (tank is only 24" deep), you can see why I am wondering about the usefullness of the actinics during my daylite period.
Thanx for the good read tho, it took about my whole dinner to get thru it.

[Poseidon]

LOL!!!

That was a short one too!!! Great post George!