How To Choose Aquarium filtration.
The topic of filtration for both aquariums and ponds is a huge subject. There are many types of filtration systems available and even experts disagree about which are the best systems. The basics are, however, quite simple and applicable to every type of captive aquatic environment.

What Is Filtration?
Filtration is a process involving mechanical, biological and chemical means to remove organic pollutive elements and other toxins that are present in an aquarium (Or other enclosed aquatic environment containing living organisms). A build up of liquid and solid fish waste primarily causes this pollution.

Why Is Filtration Recommended?
A filter will process the waste produced by fish in the aquarium providing a healthier, more stable environment. In a filtered aquarium fish will be much less prone to disease, more active and more colourful.

Types Of Filtration Explained.
A filter is a container that is filled with material called media. This media does two or three things: a) traps small particles of waste matter (Mechanical filtration) b) provides a large surface area which is colonised by a bacterium which consumes waste (Bacteriological filtration) and c) absorbs or converts other toxins which cannot be trapped or converted by a) or b) above (Chemical filtration). Most filters are supplied complete when purchased with a) and b) and the option for c) may be purchased separately. Bacteriological filtration is arguably the most important part of any filter function as this process will remove a component of fish waste called Ammonia, which is extremely poisonous to fish. Some types of chemical filtration can also remove Ammonia.

Common Types Of Filter.
The most common types of filter are Internal Power Filters, External Power Filters, Air Pump driven or Powerhead driven Under-Gravel Filters and Air Pump driven Internal Box Filters. Some Aquarium systems, such as Juwel, Mirabello, Eclipse, Tropiquarium and Fluval Uno and Duo come complete with manufacturers filtration kits already fitted.

About Internal Power Filters.
The filter consists of two sections. The top section is a submersible centrifugal pump which provides the power. The pump is attached to a canister, the bottom section, which contains a bio-foam. The bio-foam traps waste and provides a home for beneficial bacteria that consume physical and liquid waste. The filter unit is attached to the aquarium glass with suckers, back, side or corner, dependant on filter type or your choice of position. A modern internal power filter will, therefore, treat aquarium water in the following ways.

Additionally the water flow provided by the pump circulates the aquarium water and if positioned close to the water surface (Approximately 1cm ( ½”) below water surface) increases the Oxygen content as the water surface is rippled so increasing the surface area available for Oxygen absorption and other gaseous exchange

Choosing an Internal Power Filter.
Choosing an Internal Power Filter for your aquarium is easy. All manufacturers produce filters for a variety of aquarium sizes. Usually a number will identify the correct filter, ie. Fluval 2(Hagen), IPF2 (Interpet) which are for 2 feet or 60cm aquaria. Some manufacturers quote the volume of water that the filter is able to process (Eheim & others). To work out the capacity or water volume of your aquarium in UK gallons multiply the Length x Height x Width and then multiply this figure by 6.23 (Six point two three). If you require the volume in Litres multiply the result by 4.5 (Four point five). This gives the maximum water volume of the aquarium but of course, in real terms, there will be less than this as water is displaced equally by gravel and decorations so round the total down by 15 to 20%. See “How to work out the capacity (Water volume) of your aquarium” information page, for water volume of popular aquarium sizes.

Maintaining an internal power filter.
Follow the easy steps to make sure you get the best possible performance from your filter and ensure maximum life of the unit.

How to choose and maintain an external power filter.

About External Power Filters.
External Power or “Canister” filters are available from most major aquarium product manufactures and provide a potent and powerful means of controlling the artificial environment of the home aquarium. These units are the next step up from the Internal Power filter. Although more expensive than in tank units they do offer a number of benefits. The filter is a large cylindrical or square container containing the media and the top part contains the motor drive unit. The media container and the motor unit are fastened together by clips and a seal between these two parts prevents leakage. Situated remote from the aquarium they work by drawing water from it by means of a slim intake tube in the water with a strainer on the end to prevent drawing in fish or anything too large for the filter to handle. Aquarium water then passes to the filter via a flexible pipe where it is processed by the media contained within. Treated water is returned to the aquarium via another flexible pipe terminating in a spray bar. The spray bar is a long, thin rigid tube perforated with small holes and can be positioned above or below the water surface. All filters are supplied as a kit, which includes all connecting pipes. Some, but not all are supplied with basic media and taps allowing disconnection of the main unit from the intake and spray bar pipes for ease of removal during maintenance. If they do not come complete with media and taps these can be purchased separately. Most manufacturers offer a range of accessories to complement the filter kit.

Benefits of an external power filter.

Choosing an external power filter.
Choosing the correct external filter for your aquarium is easy. These filters are only suitable for aquariums of capacity 17 gallons (75 Litres) or greater. As a general rule, choose a filter which can turn over the entire aquarium volume between 2 to 6 times every hour with 4 times an hour being a good average rule of thumb . Calculate for a lower turnover for aquariums containing low stock densities or small fish and choose one with a higher turnover for heavily stocked aquariums, those containing larger fish or fish which require particularly good water conditions such as Discus or Marines.

Maintaining External Power Filters.
See details on maintaining an internal power filter above and also refer to manufacturers instructions and filter media information pages. On average an external power filter will need maintenance attention every 4 to 8 weeks dependant on aquarium type and fish stock density.

External canister filters are well worth the extra outlay and are highly recommended by Lifeforceonline.

Under Gravel filters – Air Driven.
Under gravel filtration is a traditional form of filtration that has stood the test of time and works but has largely been replaced by powered filtration and manufacturers kits that include filtration with the aquarium package.

About Under Gravel Filters.
An under gravel filter comprises a perforated plate positioned on the bottom of the aquarium which is covered entirely by the aquarium gravel. Affixed to the plate are one or two “Uplift” tubes that rise from the perforated plate into the body of aquarium water above. An “Air stone” is positioned just above gravel height inside the uplift tube and a length of hollow airline connects this air stone to an air pump situated external to the aquarium. The air bubble stream rising up through the uplift tube pushes water before it. This water is drawn from underneath the plate below and to replace this water displacement, water from the body of the aquarium is drawn through the gravel and down underneath the filter plate. In this fashion all the water contained in the aquarium is placed in constant motion from the body of the aquarium, through the gravel bed, underneath the filter plate and back up the uplift tube into the body of the aquarium. The aquarium water contains both oxygen and organic waste produced primarily by the fish inhabitants. The gravel layer above the filter plate becomes colonized by aerobic nitrifying bacteria which utilize the waste as a food supply, breaking it down into less toxic components and so purifying the water. This system works very much like the large gravel beds that can be seen at sewage processing sites. It is important that, should the air pump be positioned below the water level, a non- return valve be fitted. This will ensure that in the event of an interruption of the electrical power supply water will not siphon from the aquarium, down the airline and into the pump mechanism so avoiding a potential safety hazard. Instead of using an air pump the under gravel filter can be “Powered” by fitting a Power Head or Centrifugal pump to the uplift tube. This will make the under gravel filter more efficient as a power pump will produce a greater turnover of water through the filter bed than an air pump can. In addition the powered option produces a more consistent flow rate, which provides for a more stable filter bed and these pumps are almost silent in operation, unlike air pumps, which are noisy.

Choosing An Under Gravel Filter.
When choosing an under gravel filter it is important to choose one that is of a size that will, as far as possible, cover the entire base area of the aquarium. This is to ensure maximum circulation through the largest possible area of substrate. The slot sizes in the filter plates will vary dependant upon the make so check that the gravel type you are using is not of too small a grain size or it will drop through the filter plate slots. If this happens the void under the filter plate will clog which will reduce the filters efficiency or cause its function to cease entirely with disastrous consequences to the inhabitants of the aquarium.

Maintaining Under Gravel Filters.
In theory the filter bed should break down all waste produced in the aquarium but in practice the amount of bacteriological activity in most is insufficient to do this and there is, therefore, a gradual build up of silt within the filter bed. The performance of the filter bed can be enhanced with bacteriological additives such as “Cycle” but even with such assistance, regular maintenance is required to avoid overload and system collapse. A typical system collapse will occur quickly with catastrophic results as toxic Ammonia is released resulting in a “Wipe out” with loss of most or all of the fish stock. To avoid such an occurrence it is essential to maintain the gravel bed every two to six weeks with a four-week period being average. To do this use a gravel cleaning siphon device. This is a large bore siphon tube connected to a flexible discharge pipe. The large bore tube is pushed into the gravel bed once the siphon is started and mulm is drawn from the gravel with the water flow into a bucket recepticle.

Internal Air Driven Box Filters.
These filters, as the name suggests are small plastic boxes that fit inside the aquarium to the back or rear corner. They can be filled with filter media such as filter floss and activated carbon and utilize an air pump to produce a water flow through this media very much in the same way as under gravel filters. This type of filter is now only used in very small or budget systems, temporary set ups and also sometimes in breeding tanks. They can also be used as temporary additions to existing filtered systems, for example when packed with activated carbon to remove traces of chemicals after treatment to the aquarium.