This is a true beginner question (Actually just about every question I ask here is a true beginner question). I have a corner tank and am having some trouble figuring out how to get a light on it. When the product advertisement says "18 inches" Does it mean that the bulb is 18 inches or that the fixture all together is 18 inches.

I am looking at Coralife PC lighting, the size depends on the answer to the above question, either 18 or 24 inches. If the lights stand on legs how can I get them to fit my corner tank? Can they be adjusted?

Thanks.

P.S. I almost put this in the "New to Saltwater" section, but since this is pertaining to lighting I put it here.

Not sure I get what you are saying. Maybe Carmie can help you out, she has a corner tank, here is what her light looks like. http://www.talkingreef.com/forums/member-tank-projects/956-carmies-54-corner-5.html#post52077

The question that you didn't understand was probably how long a light is.
Whenever I see lighting for sale on the internet it is described as a 18 inch, a 24, inch, a 36 inch, and so on and so forth. Is the measurement the size of the entire lighting unit or just the bulb?

i THINK it is the entire unit.

Yeah, so do I. My tank is 36" and my fixture is about even. The legs on mine slide, so I can adjust their position. I think thats how most are.

I agree that it is the length of the fixture, not the bulb. On my 54 corner I have 29" of linear real estate. I have a 24" Solaris and it work great. All four legs are independent, I have the back legs slid in a few inches from the edge and the front legs all the way outboard.

I have a corner tank and am having some trouble figuring out how to get a light on it. When the product advertisement says "18 inches" Does it mean that the bulb is 18 inches or that the fixture all together is 18 inches.
All lighting fixtures are sold by the length of the fixture. My 36" inch PC bulbs probably measure 33.5" or so.

I am looking at Coralife PC lighting, the size depends on the answer to the above question, either 18 or 24 inches. If the lights stand on legs how can I get them to fit my corner tank? Can they be adjusted?

You need to look at the unit! I had one that I could adjust fairly easily, since you could just screw the screws into the track anywhere you chose. On my new unit, there are 2 sets of pre-drilled holes to choose from -though it's not too hard to measure and drill new ones if you need them.