Filtration For Tropical Fish

Filtration For Tropical Fish

Tropical Tank Filtration

Filtration is essential if your fish are to thrive, and your aquarium is to become the stunning visual display it should be. In nature, most fish and plants exist in an environment of continually changing water supplies -flowing rivers, large ponds, lakes and estuaries. In the natural world, such a small, static body of water could not support the concentration and variety of life found in even the most modest tank. The key to life in such an artificial environment is filtration. Filtration removes waste products from the water, and circulates clean water back into aquarium. If they are not removed regularly, the change in the chemical balance of the water could prove fatal to fish. There are three main types - Mechanical, Chemical and Biological.


Put simply, this works like a sieve. In some, water is pumped through fine 'filter media', which traps debris. Over time this filter becomes clogged and the debris must be regularly removed. Undergravel systems use a pump and raised grates to suck the water through the gravel on the floor of the tank. Mechanical filters improve oxygen levels, provide stable conditions and reduce the build-up of dangerous nitrates.

Test Kits Tropical Food Internal Filters
External Filters Tropical Heaters Tropical Treatments
Tropical Air Pumps Tropical Lighting Tropical Accessories


Chemical filtration provides a way of fine-tuning your water. Different chemically active filter media can be used to remove specific substances, adjust hardness and pH levels and remove medication following a disease treatment. Combined with a Test Kit, the chemical filter is one of the best ways to manage your water quality. For example, carbon will filter out harmful liquids, dyes, medicines, extremely fine suspended particles and contaminants.


The filter can become a useful home for beneficial nitrifying bacteria. They live there, and neutralise two of the most highly toxic compounds produced in an aquarium - ammonia and nitrite - to leave safe nitrates. To boost these “friendly” bacterial populations, use the biological aquarium supplement, Cycle, to set up and maintain your filter

Tropical Tanks

Filter systems and Oxygenation

The filter system is often relied upon to help oxygenate the water too.

Filters are extremely energy efficient and can be used to both filter as well as agitate the water sufficiently to improve oxygen levels. They require minimal maintenance and are trouble - free.

Filtration is the key to life

Internal Filters

The internal filter is perhaps the simplest to install and use, combining biological, chemical and mechanical filtration in a compact unit designed to fit inside the aquarium, just below the waterline.

The water is sucked into the unit through vents at the base of the unit by an impeller, a foam filter removes waste and allows bacteria to break down impurities, the clean water is then returned near the surface to allow aeration as the flow breaks the surface.

Small and discreet, as long as the two filter cartridges are alternatively cleaned 'say every fortnight' this system can filter the water in a smaller aquarium several times an hour.

External Filters

The External Filter is a system where the pump, filtration media and other mechanical elements of the filter are housed outside the aquarium - usually in a canister.

Water is pumped from the aquarium into the canister, through various stages of the filter, then returned to the aquarium, clean and oxygenated. The external canisters are less invasive, leaving more tank space, and make it easy to change and adjust media. Many use a multi-stage system of filtration, allowing careful fine-tuning of your water quality and the encouragement of various helpful bacteria. The wide variety of filter materials available ensures waste - free water, strong biological purification and gives you pro-active control of water characteristics

Tropical Tanks

Pre-Filter and Bio-Max

Small, inert, solid ceramic rings allow particles of waste and detritus to be removed, while encouraging the right kind of bacteria growth, controlling ammonia and nitrate levels. Choose from a basic Pre-Filter, or opt for the more porous Bio-Max.

Ammonia Remover

Removes harmful ammonia before it can affect your fish. Intended for fresh water use, it can help reduce the build-up of ammonia resulting from the chloramine in treated water.


Carbon is a natural purifier ideal for both fresh and marine water. The granules increase the surface area, trapping waste and removing urine, dyes or other unwanted chemicals. Combined with the powerful ammonia remover in Zeo-Carb, it can protect your water from impurities and harmful ammonia.

Peat Fibre and Peat Granular

Used as fibres, peat darkens, acidifies and softens water - making the ideal conditions for spawning. It is generally used in fresh water and can benefit plants too. The granular form allows more control where specific pH is required for breeding.


The initial foam screen removes the coarse and medium solid waste as the water passes through to the finer mechanical and biological media.


Filter are designed to remove toxic ammonia and nitrites from your aquarium water using a process essential for a healthy aquarium called

The Nitrogen Cycle.

Ammonia and nitrite are naturally occurring, but relatively harmful compounds. Nitrate is relatively safe. When an aquarium is first set up, the bacteria that help regulate the harmful compounds take a while to establish. Before they do, the water needs to go through the nitrogen cycle. The bacteria that begin the process are the nitrosomonas. They reproduce every eight hours, and convert ammonia to nitrites. This will take about ten days - during which time ammonia levels can be high. That is why you should always start your aquarium with just a few of the more hardy species, change water often and use Cycle to introduce ideal strains of “friendly” bacteria. After ten days, the second type of bacteria begins to populate the tank nitrobacter. This strain convertsthe still dangerous nitrites into relatively harmless nitrates. This takes about 21 to 30 days, after which all the nitrite should be gone. You should carry out as many partial water changes as you can in these first phases. Once the friendly bacteria are established, levels of ammonia and nitrite will be kept under control naturally, unless something occurs to dramatically reduce bacteria levels.