What's all that stuff?

I've had a few friends ask me "what does [random equipment] do anyway?". Here are the basics, in a very simplified manner.

In my reef tank, I have a submersible heater, 4 powerheads, a skimmer, and a canister filter. The first is fairly self explanatory, but I'll point out that submersible heaters are better for several reasons than the old fashioned ones that sit at a specific water level. First, if the water level drops for some reason, the old ones can shatter when exposed -- they simply overheat. Even when they survive the drop in water level, just a splash of cool water will do them in. Another benefit is that you can place them in a more efficient area of the tank -- next to a high flow spot works well, so the heat is more evenly distributed. And let's not forget aesthetics; hiding ugly equipment makes all the difference in a display.

Powerheads are simply submersible pumps. They can run filters, but for my reef tank all they are there for is moving water. This prevents algae/cyanobacteria from taking over (once you find and eliminate all the dead zones!), and helps deliver food and nutrients to the tiny little filter feeding animals among the rock. Some corals need high flow, and some fish, like clownfish, will actually play in the currents.

The skimmer is what confuses those used to freshwater tanks. You can actually live without this piece of equipment, but it will make your life harder. It removes organic waste... and before your eyes glaze over, here's the easy example. Ever walk on the beach and see the nasty brown foam the waves leave there, especially on a windy or stormy day? Yeah. The skimmer removes that gunk from your tank. If you do enough water changes regularly, you can live without it, but it's a nice safety net for even the most conscientious of us. There are a few out there who worry that it will remove bad and good alike, and I see the point, but I certainly wouldn't tell a beginner to go without one. (There are many, many articles on the internet about skimmers. As I said, this is the short and quick version.)

The canister filter, in a tank with a ton of live rock and a protein skimmer, is probably overkill. I use it mainly for circulation, and for the ability to chuck some carbon or phosphate remover in if it becomes necessary. I could probably do quite well without it! In this kind of system, most of the filtration is actually done by the rock, which is why you shouldn't skimp on that particular purchase. (It is tempting when starting out... "It's just a pile of rock! I want fish!".)

One thing I did leave out at the beginning -- the lighting. There are a billion-ty articles about lighting out there. About the color temperature, the watts/gallon, or watts/inch depth, or the kind of bulb, etc. Many people much smarter than I have quite a lot to say on the subject. In the end, I chose power compact. It's relatively cheap, fine for most soft corals, and easy to find. To really get into the issue of lighting, though... that's a post for another day.