Discussion of the week ~Coral Lighting Needs~

[mojoreef]

Ok as requested by our members here is the topic of the week.

What constitutes low, medium, and high light levels. and which corals like each?
Ok so lets not argue to much, but lets hear everyones opinions.


Mike

[Geoff]

i like this discussion.

how do you determin how much light do you have? is watts/gallon a useable reference. with the different spectrums of light produced by bulbs now, how do we know we are getting the correct spectrum to whatever we are keeping, in the intensity that they need. just cause you have a 400w mh bulb at 4500k does not mean you have enough light for a clam.

i can see my 400w saki's with actinics is enough light for my clam and acros, because they are growing. at what point do the clam and acros start suffering.

G~

[Reedman]

I'd also like to hear opinions on how long the photoperiod should be. Some texts site that the MH useful lighting period is as little as 4-6 hrs yet I know of almost no-one that has theirs lit for less that 6-8 hours.

How much of the lighting time is useful to the corals and how much is just looks for the tank owner?

Is there a benefit to a shorter photo period occasionaly or longer term? Not everyday on the reef is a sunny, clear day (most are though).

How do we know that rapid growth = health in our tanks? This may not be true at all. If a dog grows too rapidly this is considered unhealthy and can have negative long term affects. Could this also be true of corals (i.e. not enough base growth, and a top heavy coral that is not strong enough to support itself. Or shading itself out at the base before it gets a good foothold).

Just some things to ponder.

Great topic Mike. Should be full of opinions and hopefully some scientific information too

[Geoff]

as for lighting duration i have no idea. i have an aquacontroller II controlling my system. i went with the built in daylight program. this adjusts the amount of light for the entire year. i figure it sounds like a good idea to me. i am sure i will not get the growth like those that keep thier systems at optimal 100% of the time, but i know i would get bored if i had the same daylight all year long.

the aquacontroller also has a couple miss-sends over the course of the day. so for a couple of minutes at random a light will go off. i think this will simulate a cloud to some extent.

G~

[Mkelly]

Light meter. Get one, 80$ bucks. Any good electrical supply house should be able to get you one or if you have heard of WW Grainger.
http://www.grainger.com/Grainger/wwg/start.shtml
These guys stock everything under the sun.

This makes a lot of sense to me...

"Most of the corals that are imported today are from waters ranging from 10-20meters deep (33-66 feet). If you have ever gone snorkeling or scuba diving, or just watched an under water video, you know that at those depths, the color of the water is blue. The orange and red spectrum is drastically reduced; thus there are more violet blues and greens at those depths. Unfortunately, the higher the Kelvin rating of the bulb, the lower the intensity. So, therefore you will need a higher wattage bulb if you decide to use a 20,000K-rated bulb. "

You can read the whole article here..
http://www.masla.com/reef/lightingneeds.html

So it would seem that spectrum is related to the creature,and the depth at which it lives. Naturally we would probably have to scale back due to a shallow depth of most tanks. Conversely most shallow water or lagoon type creatures would need more light and a reder spectrum lamp.

[Toadfish]

My question is what is the differential in intensity from 20K's to 10K's? For instance how many watts at 20K would be needed to generate the same intensity of 2 175w 10k's? Is there a formula for this?

[laddy00]

Toadfish
check out this study done on some mh lamps. It goes over some of the differences in not only the Kelvin ratings but also different brands
http://www.personal.psu.edu/faculty/...omparison.html

[laddy00]

Actually that link was for using the same bulb on different ballasts. Here are three links for a series of articles about spectral analysis and intensities of several bulbs.
Part 1: New 400-watt Lamps, http://www.animalnetwork.com/fish2/a.../1/default.asp
Part II: Used 400-watt Lamps http://www.animalnetwork.com/fish2/a.../2/default.asp
Part III: New and used 250-watt Lamps http://www.animalnetwork.com/fish2/a.../2/default.asp

[Sallylightfoot]

Originally posted by Mkelly
Unfortunately, the higher the Kelvin rating of the bulb, the lower the intensity. So, therefore you will need a higher wattage bulb if you decide to use a 20,000K-rated bulb. "

WOW!! That is a new one on me. I always thought by going 10K over the 7100K was doing them a favor. Thanks for the link. I am going to really check it over good!!!

[laddy00]

One thing I don't think most people realize is that the 6500K Iwasaki actually puts out more light in the blue spectrum than most 10K maybe even 20K bulbs. The iwasaki just happens to put out more of the yellow and red spectrum so it tends to look more yellow than blue. If we take into accout our corals first and aesthetics second it would seem to me that we should try to use the 6500K bulbs more than the 10K and 20K for the sake of our inhabitants.

[Casey]

I agree 65 k is the closest to daylight I like the actinics to make it look bluer.

[Sallylightfoot]

Well, went to the site and got to this part....................."The color temperature of the bulb is referenced in degrees Kelvin (K), with the higher the color temperature, the whiter the bulb. That is because the violet blue and green parts of the color spectrum prevail. If the color temperature of the bulb is lower, the warmer the appearance of the light, with the orange and red hues of the spectrum dominating. One of the main topics of debate is which Kelvin rating is best for which corals so as to keep their natural colors." Now I am confused. Reading this it makes me think the higher the K the more blue??? Please clarify for me if you can.
TIA,
Sally

[Buzz_Hog]

Originally posted by Geoff
i like this discussion.

how do you determin how much light do you have? is watts/gallon a useable reference. with the different spectrums of light produced by bulbs now, how do we know we are getting the correct spectrum to whatever we are keeping, in the intensity that they need. just cause you have a 400w mh bulb at 4500k does not mean you have enough light for a clam.

i can see my 400w saki's with actinics is enough light for my clam and acros, because they are growing. at what point do the clam and acros start suffering.

G~

Geoff,

I have a Suamosa clam... When I got him, I had a 2x55 PC at 6,500, an 18,000K 20 Watt NO, and a 20 watt 03 actinic. Total wattage was 150 watts on a 29 gallon tank. The clam did not seem to thrive in that environment, but it didn't look like it was suffering.. (although I can't really tell if it was suffering unless it showed major signs of distress)

I have upgraded my lighting to a 250 watt 10,000K Ushio and 2x55 03 actinics. I run my lights from 11 AM until 12 PM... I can definately tell that the clam is , well, happy as a clam now. I see extension of his mangtle like I have never seen before. He is more active in moving himself into different positions, and although I can't verify that I've seen growth, I do have a good feeling that he is growing.

I just wanted to add this to the collection pool of lighting situations, and observences of their effects on clams.

MH and PC Actinics are approx 10 inches above water surface with a single spider reflector. Due to the height, and open back on my Jimmy Rig canopy, I suffer a lot of light loss due to disipation. I may rework the canopy and lower the lights closer to the surface to see what effect this will have.

Currently running, I have approx 12.4 watts per gallon.

[cyberchef]

Buz, look below the mantle at the edge of the shell. If the clam is growing the new shell will be at the edges and will be lighter in color than the rest of the shell.

[Mkelly]

This is gonna sound odd but I raised my lights to clean the tank the other night and it actually looks brighter. Has to be an illusion I'll toss the light meater in the tank and check for sure.

Photometrics are an odd thing I know for a fact you loose light as you distance yourself from a fixture. The fc ( foot candles ) reading will drop, but how it looks brighter is a mystery to me.

Sally that is correct the higher the K rate the more blue lower k is more red/pink aka warm.

This applies to film but the principal is trhe same and should help you grasp the scales..
http://www.mlkstudios.com/course/light/kelvin.html

This I havent read yet but looked interesting so I linked it for myself when I get home I'll read it..


http://www.animalnetwork.com/fish2/a...ov/features/1/