color and growth

[mps9506]

I just wanted to ask, how many people running metal halides have really noticed a difference in growth rates when changing the bulbs they run?
When I changed from 6500k Iwasaki to an AB I noticed zero difference in growth rates and noticable improvement in color.
I had a buddy that claims the same thing. It seems as long as water quality is consistent throughout the day my corals grow most consistently. When I start getting flucuations, growth slows down.
I've seen the 250watt bulb comparsions on RC, most of the time Iwasakis win hands down regarding PAR, but how much is really nesacary for good growth? My Ab's seem to pump out enough to make most digitata frags grow insanely fast and put nice white tips on my acros. I'm waiting for my coralvue to burn in to see how similar corals react to it's lighting, as it appears the coralvue has less PAR than the AB, although it sure does visually appear brighter...
Anyways, just some thoughts, looking for input from anyone.
Mike

[chinoxl3]

My experience, I noticed some growth when I switched from 6500 to 10k Ushio. However, I did not noticem major change in color except a little to the green. I just switched to 20K, so we'll see how that turns out.

[mnreefman]

chinox, i noticed good growth with the 20k but sps turn a shade of green... btw i am going back to the 10k's

[Pro_builder]

I am running XM 10K's and love the coral growth and the look of the tank, doesn't seem to be as white of a look.

[Brucey]

I haven't changed mine yet, I run 14K's anyway but they are a year old and are due for replacement ...... Anyone else replace theirs every year (as the LFS told me too .... but their trying to make $$$$ tooo), or is that over rated. Mine are a year old and I haven't noticed any change in the corals ..... plus I haven't got any money

[mps9506]

Originally posted by Brucey
I haven't changed mine yet, I run 14K's anyway but they are a year old and are due for replacement ...... Anyone else replace theirs every year (as the LFS told me too .... but their trying to make $$$$ tooo), or is that over rated. Mine are a year old and I haven't noticed any change in the corals ..... plus I haven't got any money

I replace yearly, the colors of the bulb seem to shift. I had a 7 month old ab next to a brand new one and the new one seemed much whiter...
Mike

[mnreefman]

i replace my 175s every 10 months

[Boomer]

When I changed from 6500k Iwasaki to an AB I noticed zero difference in growth rates and noticable improvement in color.

Growth is a function of PAR/PUR or total irradiace, to include "food" and K plays almost no roll, if any at all. K is mostly a function of change in color, as observed by you, not that the coral has changed . It is our eyes playing tricks on us or in many cases the corals, by certain lighting, which produce a greater response of fluorescing substances.

[Craig Manoukian]

So what is the range of PAR values that are best for reef tanks? The information by kelvin rating would be sweet.

[Cougra]

PAR and Kelvin are two different things Craig.

Kelvin is the measure of the colour of a bulb. This will take a little bit of explaining so please try to bare with me....

Kelvin is actually a temperature scale. When an object is heated up the electrons start to jump around faster and faster. When they jump move fast enough they jump to a different level in the adom and a photon is released. The faster the electron is moving (more heat) the higher the frequency (measurement of wavelength not how often) of the photon released. The frequency of the photon will determine the colour of light the proton will be percieved as.

Now many tests have been done to determine how much energy (temperature/heat) needs to be added to objects to force an electron to jump to a state that will produce photons in a frequency range that the human eye can see (Colour spectrum). In order to standardize these test they used a black object and heated it up until it appeared a specific colour of light and then noted the temperature required to get this temperature.

Therefore when we say that our bulbs have a temperature rating of 10,000K, this means that we would need to heat up a black object to 10,000 Kelvins (~17540F or ~9726C) before it will give off the same colour of light as the bulb.

As for PAR, someone else will have to explain that one as I don't completely understand that terminology.

[Boomer]

To add to Mike's post and go further post

Blue light puts out much more energy than red light. Almost twice as much. For example, 380 nm, which is UV, vs. 750 nm or far red puts out 1.97 times more energy in joules.In caloric terms it is 75.13 kcal vs. 38.13 kcal. But you don't have to go through all the fancy math equations to prove this. It follows a very simple short cut 750 nm / 380 nm = 1.97 times greater, as 75.13 / 38.13 = 1.97 times greater also.

Kelvin

Look at this SED (Spectral Energy Distribution) Curve.




Blue = Iwasaki Aqua 50000K Brown = Iwasaki ColorArc 6500K

400nm is blue light and 700nm is red light. The Intensity is a functuion of watts of light produced, in MH it is usually watts / 10 nm bandwidth.

If you added up all the freq of the 6500 bulb it would give a final K of 6500K, same for the 50,000. Notice that the 50,000K has a very high peak in the blue and not much of anything else. Now look at the 6500K, it has little blue light and allot of green and yellow. Thus, the more peaks you have or higher the peaks are in any color the more it will skew to that color. So, the 50,000K bulb will be much more blue and the 6500K much more green-yellow. Now if you looked at the PAR of these lamps the 6500K would have much more, because of all the peaks in the yellow-green. People get misled with the concept that the light color they are getting is allot of blue, therefore use bulbs with allot of blue or make the tank look more blue. If you were a diver or have watched TV on coral reef specials or what ever, most of the time when they turn off the lights the water is not blue, but more of a dirty yellow-green. That color is telling what they are getting to a point. Some how, people seem to get the idea that more blue is always better, when in fact the PAR can often be lower.

Oh piss on it Craig, it will be easier for you to just go read this and then come back with any questions. Rather than me rambling on for two pages

http://www.coralreefecosystems.com/l...tput Analysis:


On a normal day the North Light is 8500K or light blue. An overcast day is about 7000K and "daylight" is 6500K. Summer sunlight is usually around 5500K. And those very yellow street lights you see are about 2000K. A clear Mercury Vapor is 6000K and a Candle is less than 2000K. And a std MH is 4500K.

Light = Is the radiant energy produced by a light source. It may come to your eye directly or it may be transmitted or reflected from an object

Color = Is the interaction of the light source, the reflector or transmitter and our own ability to detect the color of the light. Different light sources radiate different wave lengths of light, influencing the *appearance* of the colored object. If you really wanted to show of your tank and all its colors, load up your hood with "Enhancement lights" The blue will be really blue and the red really red. You see people doing this with many of their photo's. Bring it into something like PhotoShop and slide around the hue and saturation bar. The colors of the corals are now much more colored than they really are, but the pics sure are impressive. You have, in short, changed the natural or real K of the image.

[Craig Manoukian]

Thanks Michelle and Boomer. Will read and get back with any questions.

[Scooterman]

Originally posted by Boomer
You see people doing this with many of their photo's. Bring it into something like PhotoShop and slide around the hue and saturation bar. The colors of the corals are now much more colored than they really are, but the pics sure are impressive. You have, in short, changed the natural or real K of the image.

PhotoShop is a wonderful tool, we play around with our lighting so much to get the colors to look the way we perceive them to be, instead of their actual colors, is this right? This is more appealing, instead of the yellowish colors at 65k?.

[jks1]

thanks guys- Ill reaqd too

[EdgeKrusher]

Yea I'll read too , that was over my head. I'm frustrated now, I don't understand it. Thanks for the links.