The filter keeps the whole aquarium moving. It physically cycles the water around the tank, and without it everything inside would be dead and stop.
The filter is the sewer treatment works of the aquarium, removing large chunks of waste manually with foams and floss, and growing good bacteria that will change toxic waste chemicals into safer components.
In most examples, the filter is a box that sits in, or just outside, the aquarium, it has a pump inside that pushes the water through filter media (the foams, floss and bacteria we just talked about) and out the other side to re-enter the aquarium.
They come in all shapes and sizes for all different aquariums but every aquarium should have one, that’s the important part.
The lighting is your aquarium’s sun.
Everything needs light to live and aquarium lighting is designed to provide the right light to help plants grow, fish thrive, and (when used in the right time cycles) keep algae at bay.
Lighting can come in bulb form, the more traditional style, or LED, the more efficient of the two, but both will do a good job depending on the needs of your tank.
It’s important to control your aquarium lighting to mimic a natural cycle. Too much light and your tank will turn green with algae, not enough and you’ll have dull colored fish and dying plants.
When keeping fish from tropical waters a heater is an essential part of the aquarium kit. A large majority of aquarium fish come from regions of the world that are warm, and the waters are too!
Heaters come in a variety of formats, but the most common are thermostatically controlled, sealed glass tubes with an element inside that is fully submerged under the water. Often the manufacturer will pre-set the temperature, however, these heaters usually have a thermostatic controller to allow you to dictate the temperature. Follow the manufacturer’s instructions to fit the heater correctly and always use an aquarium thermometer so you can ensure everything is working properly.
Another variety of aquarium heater are flat heaters that are programmed to maintain a temperature above the ambient temperature. They are constantly producing a set amount of heat and the water temperature should be carefully monitored in the hotter months. These heaters can be quite flexible, fitting into the aquarium in several ways: Hanging the heater on the side of the aquarium, tucking it away in the filter (depending on the aquarium design) or burying in the gravel.
Other equipment you might see available for your aquarium are air pumps and air stones/air ornaments.
As well as looking pretty, adding aeration to your aquarium will benefit both fish and plants, who need oxygen to live.
Oxygen is scarce in water, therefore circulating the water using bubbles helps to take oxygen from the surface, as well as driving out carbon dioxide, which is poisonous.
Although your filter will circulate the water, the best way to ensure optimal gaseous exchange is to use an air pump and air stone.
Gravel, or substrate as it is also known, is the material that you add to the base of your aquarium.
It comes in many shape, sizes – from almost sand to stones - and a variety of colors. Substrates can also be artificial, with a variety of brightly colored option available.
As well as the visual look of the gravel, it also serves the purpose of anchoring any ornaments and plants, and can hold nutrients for live plants to take up through their roots. Always use specialist aquatics gravel and thoroughly wash in plain water before adding it to your aquarium.
You will also add fish, plants and decorations to your aquarium, see the specific articles on these.