2torial #0705: Learn2 Set up a Freshwater Aquarium Choose your equipment You might be a little overwhelmed by all the equipment available for your fish. Who knew they'd need so much? But fear not--here's a list of what you should have to get started: 1. A filter. There are three basic types of filtration: mechanical, biological and chemical. Most aquarium pros prefer a filter that combines a mechanical function--or a "pre-filter"--to trap particles like plant debris and uneaten food, and a biological function, which breaks down the dangerous ammonia that comes from fish waste. Chemical filtration is used for foreign chemical toxins, like soap or perfume. If you're careful about what goes into your tank, you shouldn't need this type (although many filters come with chemical filtration included). What you need may depend on the size of your tank, and the type and amount of fish you want. Other considerations are the filter's noise level, maintenance and, of course, cost. 2. A heater. The vast majority of aquarium fish are tropical, so chances are you'll need a heater to keep the temperature steady--usually about 78F (25.5C). There are many types and the cost can vary. Some heaters are completely submersible, while others submerge partially, with the controls on the outside of the tank. 3. Gravel. The general rule of thumb is one pound of gravel for every gallon of water. The wrong type of gravel can change the water content and harm the fish, so buy it at the pet or aquarium store and make sure it's for freshwater use. 4. Plants and rocks. These are not just for decoration. Fish need markers to remember their territory and places to hide from the more aggressive fish. Just make sure whatever you choose is safe. Synthetic decorations should be free of any chemicals (soap, perfume, paint and so on) and well cleaned. 5. A thermometer. This lets you verify that your tank is at the right temperature. You can buy models that attach to the outside of the tank or that are submersible. 6. A siphoning tube and bucket. You'll use these to fill the tank and change the water (about 10 to 20 percent of the water should be changed every month). Always make sure the bucket is clean; it's a good idea to use it only for the aquarium. 7. A fish net. When you change the water, you'll need to move your fish temporarily into another container. An aquarium net makes that process a lot easier. 8. Water testing and purification kits. Technically, you could keep a healthy aquarium without any water tests or purifiers, but it's always good to be safe, especially if you use municipal tap water (which usually contains chlorine or chloramine--toxic to fish). The kits are usually cheap and simple to use. Optional materials. You mean there's more? Well, only for looks. Feel free to get more decorations--driftwood looks particularly nice (boil it briefly before putting it in the tank). Air pumps provide that bubble aesthetic and can be camouflaged by rocks or the classic treasure chest. (Note: due to innovations in filters, air pumps are not necessary for a healthy tank.) And while a sponge with a plastic scouring pad is usually enough to clean the tank, special tools such as razorblade scrapers or magnetic cleaners are available. Note: some dish sponges contain chemicals that can be harmful or deadly to fish. When cleaning your aquarium, you should only use sponges made specifically for that purpose. Step 4