[Redbeard]

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