Aquarium Equipment

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For new fish keepers there can be an overwhelming array of equipment available. Understanding the basics of filters, lighting, heaters and air pumps will help you to make the right choices

Internal and external aquarium filters

Heaters, filters and lighting are all important components of a tropical aquarium and there is a wide choice of each available. Choosing the correct system can be a little tricky and all have to be installed and running before the first fish are introduced. Some all-in-one aquariums will contain suitable lighting, heating and filtration as part of a package and are ideal for first-time buyers. Other items of equipment also have to be considered, particularly for maintenance purposes. Cleaning equipment such as algae pads and gravel cleaners are required for regular maintenance. A small net for removing debris will be useful. Containers for moving water should also be bought new and used only for the aquarium to prevent contamination.

These are all additional items that need to be considered, however, it is the filter, heater and lighting that are the most expensive and important items.

What does a filter do?

All filters work on three basic principles; mechanical, biological and chemical filtration. Mechanical filtration is the removal of visible debris and will help to keep the aquarium water looking clean and clear. A filter normally carries out mechanical filtration by the use of a pump to draw water through a sponge, which traps any debris. The sponge can then be removed and cleaned. Some filters use a number of different grade sponges so that larger debris is trapped first, followed by finer debris. The process of mechanical filtration is largely a benefit to the appearance of the aquarium, the fish do not mind if the water looks dirty. In many cases, tropical fish do not come from naturally crystal clear water.

The sponges used in filters are more importantly used for biological filtration as well as mechanical. Biological filtration uses bacteria that grow on the surface of the sponges to remove dangerous pollutants such as ammonia.

Waste from the fish and from fish food is released as ammonia, which is highly toxic to fish and must be removed from the water. In biological filtration, bacteria use ammonia and convert it into nitrite, which is slightly less toxic. A second group of bacteria then convert the nitrite into nitrates, which is only toxic at high levels. A large number of bacteria are needed for biological filtration, to ensure that enough bacteria are present, filtration media has a very high surface area on which bacteria can settle. In larger filters, specialised biological media with extremely high surface areas can be used to increase biological filtration.

The third type of filtration is chemical; this involves the use of special filter media that removes chemical pollutants, which are often found in tap water. Chemical filtration is not an essential part of the filtration process but it is useful, and can prevent many problems.

Types of aquarium filter

There are three main types of filtration available for freshwater aquariums; undergravel, internal and external filters. Undergravel filtration works by drawing water down through the substrate and then up a tube back into the aquarium. The water movement is powered by an air pump or powerhead (water pump) on top of the tubes. The substrate acts as a mechanical and biological filter, trapping debris and providing a medium on which the bacteria can grow. Although undergravel filters are relatively easy to maintain, they are difficult to modify and may cause plant growth to be limited (plants do not like the movement of water and oxygen around the roots). The cost of an undergravel filter and the pump(s) to power it is similar to the cost of an internal filter. Because most modern internal filters are equally as good, and sometimes better than undergravel filters, the use of undergravel filtration is far less popular than it used to be.

Internal filters

An internal filter normally consists of a canister attached to a pump. Inside the canister is a sponge media, which acts as a mechanical and biological filter medium. As water is drawn through the canister, debris is trapped in the sponge and bacteria convert ammonia and nitrites into nitrates. Some internal filters have special chambers for additional media such as high surface area biological media or chemical filtration media. An internal filter is the most popular choice for new aquariums. Internal filters are easy to maintain, accessible and perform effective filtration for most aquariums.

External filters

An external filter is basically a larger version of an internal filter except that it is placed outside the aquarium. Water is drawn from the aquarium, through a pipe, to the canister where it is passed through various medias and then pumped back into the aquarium. The much larger canister size allows more filtration media to be used and hence, better filtration. Because an external filter is outside the aquarium, it can be hidden in a cabinet and allows more room in the aquarium for decor. In aquariums with particularly large or messy fish or a high stocking level, an external filter offers a much better form of filtration.

Choosing a heater

There are a number of different brands of heater-stats available although there is little difference between them. More expensive heater-stats may be a little tougher, so can be considered for aquariums with large fish. Cheaper heater-stats may have a shorter guarantee period, although this is not an indication of reliability. A heater-stat is a combination of a heater and a thermostat, which is housed inside a sealed glass container and is designed for use underwater. The thermostat can be set to a specific temperature and will only switch on the heater when the temperature drops below that level. Most modern heater-stats will keep the aquarium within a degree of the set temperature. Heater-stats are available in different sizes based on the power in watts that the heater uses. Larger aquariums need higher wattage heaters than smaller ones. There is normally little or no difference in the cost of different size heater-stats although it is important to get the right wattage for your aquarium. If the wattage is too low, the heater will struggle to maintain a constant temperature, if it is too high, there is a risk of overheating.

Lighting for fishtanks

Although there are a number of different types of lighting for the aquarium, fluorescent lighting is the most commonly used, and the most suitable for new fish keepers. The fluorescent tubes used in aquariums are not the same as household tubes and are designed specifically for aquarium use. A basic system consists of a starter unit, or ballast, which sits outside the aquarium and the tube, which connects to the ballast via a cable at each end. The tube connectors are usually waterproof so condensation or splashing of the tube is not damaging. The benefit of fluorescent tubes is that they run much cooler than other forms of lighting and are relatively cheap to run. For instance, a light tube for a 90cm (3 foot (36")) aquarium will only run at around 25 watts, in comparison a normal household bulb typically runs at 60 watts.

There are a number of different types or colours of aquarium fluorescent tubes. Some are designed for plant growth, whilst others are optimised for showing up the colours of fish. For the best appearance all-round a full-spectrum light tube will produce a pleasing white light and is also relatively good for plants. If you do intend to keep a number of live plants or your aquarium is quite deep then it may be worth investing in a second light tube. Remember that a second tube will require its own starter unit, although it is possible to get dual starters, which control two tubes. The starter units must be the same wattage as the light tube to work effectively.

Air Pumps

The fish in your aquarium require oxygen to respire, or breath. Oxygen enters the water through the surface and waste carbon dioxide is released. The rate of exchange between the air and the water depends on the surface area or the surface movement. A large surface area or a highly agitated surface allows a greater gas exchange, which in most cases is beneficial for fishes. The main function of an air pump is to introduce bubbles, which rise and agitate the surface, increasing the gas exchange. The bubbles themselves do not introduce a noticeable amount of oxygen, but by increasing the surface movement, allow more oxygen into the water. In most aquariums, the aquarium filter more than provides for the amount of surface movement needed to introduce sufficient amounts of oxygen. An air pump is therefore not a necessary item of equipment. Air pumps can be useful in situations where oxygen levels can become low, such as in highly vegetated ponds in the summer or when using some aquarium treatments which may use up oxygen. Air pumps can also be used for purely decorative purposes, or to power some small filters or gravel cleaners but for most aquariums they are unnecessary.

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