Lighting in Layman's Terms?

Most everything I've read (print and on-line alike) use terms like low, medium, moderate, high, bright, strong, intense, etc. when recommending lighting for a particular specimen. Some refer to the type of light (PC, VHO, MH, etc.) and/or the degrees Kelvin of the light the subject was photographed under. They don't generally refer to things like PAR and perceived energy, or watts per gallon. They may suggest placing something near the top, mid tank, or at the bottom. How do they know how deep my tank is anyway?

Here's a cut and paste I found on my notepad, I don't remember where it came from but I was wondering who agrees or disagrees on weather or not this information is accurate. I mean accurate enough to use as a guide for selecting livestock for our display tanks.

5.LIGHTING RECOMMENDATIONS

Each coral has a number written on the bag. This number correlates with the lighting recommendations detailed here.

1 = Very intense light requirement, 400 watt metal halides with placement near the top.

2 = Intense light requirement, at least 250 watt or stronger metal halides with coral placed in top third of the tank.

3 = Moderate light requirement, multiple VHO fluorescents or 175 watt metal halides with coral placed mid tank or higher.

4 = Low-moderate light requirement, place coral lower in the tank.

Anybody know where that came from?

According to that my 2x175w 10000 K MH lighting would limit me to only those specimens with a moderate light requirement placed mid tank or higher. This is the same lighting Tullock used for the 50-Gallon Clam Lagoon which he says "demands intense lighting" in the book Natural Reef Aquariums. That tank is stocked with several species of "baby Tridacna clams" including T. crocea. It also has "various species of Acropora" among other things. In the pictures it looks like the clams are on the sand bed. It's a beautiful tank and very much like what I'm trying to accomplish.

Is there any consensus when it comes to the generic terms that merchants use when referring to how much light something requires?

My wife was impressed the first time she walked into the kitchen one morning before the sun was up and didn't have to turn on any lights to make coffee, I'd just set up a tank in the dinning room with a F20T12 wide spectrum timed to come on about the same time her alarm went off. Not long after that I put a 2x55 PC on a tank in the living room. Simultaneously we both said, "Wow that's bright!", now you can sit on the end of the sofa and read without turning on the lamp. Several months ago when I turned on the 2 175 watt metal halides over the 50 gallon tank also in the living room I started thinking that the plant tank over there isn't really all that bright after all. One day I went to the hydroponics supply store and saw fixtures that wouldn't fit in my car and bulbs the size of basket balls so I decided to continue growing my lettuce and herbs in the backyard for the time being.

What does it mean when they say medium, moderate, bright, strong, intense? Will T. crocea be happy in my tank? How about Acropora? Maybe some zoanthids? I just don't want to kill something simply because I didn't understand what it needed in the way of light.

Any feedback would be very helpful.

Ted

 

You are going to hate me, but light is only part of the equation. If we look at the natural reef we see a lot of softies and clams in the shallows, but you have to go to the outer slope of the reef to see the big SPS and LPS corals.

The shallower reef will be closer to the sand, higher in nitrates and phosphates, and along with the natural lighting be conducive to to those animals with those requirements.

The outer slope will be further from the sand bed and have more exposure to currents. The sun delivers all spectrum of lights and has the intensity to deliver the right spectrum even in deeper water.

The lighting intensity is a combination of watts and the PAR value, and the Kelvin rating is a measure of the spectrum of colors the light can produce.

It is very helpful to examine pictures of the natural reef and pay close attention to where and what type of animals are in relation to the surface and the bottom. This coupled with coral books, ie. Eric Bornmans, will go along way to help you undestand this complicated issue.

Remember that in the lighting game the more watts and the more PAR the more range of animals you can keep.

There are some general guidelines, but the needs of individual animals and the depth of your tank are what will determine the lighting requirements.

 

Craig,

Just want to correct a few things that you said, but over all you hit the nail on the head. I am a plant physiologist so I spend a lot of time thinking about light. I spose a lot of that has to do with the fact that I study photosynthesis (well thats the short version anyway). The Kelvin rating of the bulb has more to do with how it apears to us then the actual spectrum of light it produces (the appreance issues holds for Lumens and CRI as well). Watts would be a measure of how much energy the bulb uses, not how much it produces. Though you would assume the more it uses, the more it puts off. Point is it is not a measure of intesity. PAR is the only safe bet to go by. Bigger PAR, more energy you to have drive photosynthesis and the more light demanding things you can keep.

The other thing to keep in mind is that the range over which a photsynthetic organism can be acclimated is generally quite large, which may have a lot to do with the reason the lighting needs of these organisms remain so crudely deffined.

 

Ok...how can someone else have the same user id as me. The only thing different is the capitol letter in the name. Not that it matters but may cause some confusion.... :-/

 

I was wondering the same thing! Geuss the logins are case sensitive. Or you are my alter ego. LOL

 

[quote author=Craig_Manoukian link=board=lighting;num=1094095591;start=0#1 date=09/02/04 at 13:11:56]You are going to hate me, but light is only part of the equation.  If we look at the natural reef we see a lot of softies and clams in the shallows, but you have to go to the outer slope of the reef to see the big SPS and LPS corals. [/quote]

Thank you, I've never had the opportunity to visit a natural reef and didn't know that. It sounds like for a more natural looking display it would be better to put softies (Octocorallia?) in a "clam lagoon". Do you ever see any SPS or LPS in the shallows or clams on the outer slopes? BTW, I don't hate anybody that's willing to take the time to share some knowledge with us newbies instead of just saying do this or don't do that or read this without any explanation. I may not always like what I hear but if it helps me to successfully establish a mini-reef that's what it's all about.

[quote author=jay link=board=lighting;num=1094095591;start=0#2 date=09/02/04 at 18:09:15]The other thing to keep in mind is that the range over which a photsynthetic organism can be acclimated is generally quite large, which may have a lot to do with the reason the lighting needs of these organisms remain so crudely deffined.[/quote]

Thanks, that's encouraging. Is it true that acclimating (to a new lighting system) is really not that critical if the subject is being moved to a tank where the lights are LESS bright, strong, intense, etc.? I mean I'm just guessing that most coral propagators are using brighter, stronger, more intense, etc., lights than the 2 175 watt 10,000 K metal halides over my 50 gallon tank. Is that a safe bet? (my tank is 48Lx18Hx13D)

[quote author=Redbeard link=board=lighting;num=1094095591;start=0#0
date=09/01/04 at 20:26:31]I just don't want to kill something simply because I didn't understand what it needed in the way of light.[/quote]

Maybe someone could give me some ideas about what I shouldn't try to maintain under those lights.

Thanks,
Ted

 

Hi there!

I'm a new comer and would like some advise on reef lighting as well. I got a 50g tank with SPL corals and carpet. I had checked on every thing and seems to be normal but the SPL seems to be dying slowly. Is it because of the lighting that I am using?

 

Lazaroo,

A lot of LPS corals like torches, frogspawn, bubbles, etc. like to be target fed meaty foods in addition to good lighting and good water conditions.

Redbeard,

With a depth of 18", you should be able to keep most animals with 175w 10k MHs. Most of them put out a pretty good par. Obviously it varies with the ballast and bulb but you should be able to keep most things well with the exception of a few species of light demanding clams. You could keep those as well if placed higher to the top. I have a friend with a coral farm and he breeds SPS well with just 175w MHs.

Regarding the coral reef zonation, it gets even trickier as there are patch reefs in the middle of the lagoons that rise up out of the middle. Even though the lagoon has a lot of turbidity, these patch reefs are fairly nutrient free as they are closer to the wave action at the top. Most people have been taught that currents bring food to coral reefs and in actuality, the opposite is true. Coral reefs are productive and create their own food and the currents remove the excess nutrients from the reef. Here is a good link on <<Coral Reef Zonation>>.

 

Thanks for the input, inwall75.

One thing that I want to keep is a crocea. How close to the light source would it's mantle have to be to? The lights are about 6 inches above the water. The highest rocks are about 6 inches below the surface.

Ted

 

To help me make sense of the myriad facts regarding lighting, I've written facts down in a notepad document as I came across them in posts. Here's a copy of what I have written. Hope this helps a bit.

But first keep in mind that some of these terms are relative. Statements like "intense light" can be misleading. Take for example the bluer hues deeper down. This is a "lower Kelvin" rating, meaning less PAR, but we can take a high quality actinic bulb, say a T5 at 85W, such as is overdriven a la Icecap ballast, and would certainly describe this as intense. It would be screaming in "intensity" but produces a relatively low PAR.

OK, here's the facts as I know them so far:

10K white, 20K very blue (actinic).

50/50 half white, half blue.

Lower K is blue, has less PAR than 10K, which is a "higher K" than 20K. So, the higher the number the lower the PAR, and the deeper it represents in the water column of the ocean.

Above 6.5K, is considered actinic by some. 5.5K simulates sunlight at sea-level, a few feet down, it's 6.5K

Between 10 and 14K simulates light on a shallow reef.

Lower Kelvin, higher intensity, more PAR. 5.5K is a low Kelvin number, 20K is a higher kelvin number.