How to Install Filters for a Marine Aquarium

Place an undergrad plate in the base of the tank, just as you would for freshwater system. Before you do this, make sure that you place a slab of expanded polystyrene beneath the tank to support it and to cushion any irregularities in the surface of the stand. If you have any doubts about the tank, test it outdoors by filling it with tap water and checking it for leaks.

Cover the entire surface of the filter plate with a layer of well-washed coarse medium, such as coral gravel or dolomitechippings.You can buy this from your aquarium dealer.Do not use the kind of gravel recommended for freshwater systems. Spread the medium out into a layer about 5cm(2in) deep.

Trim a gravel tidy (a sheet of plastic mesh) to fit and place it, curl downwards, over the medium. This prevents mixing of the media and stops fish digging down to the plate.

Then add a 5cm(2in) layer of unwashed coral sand on top of the gravel tidy mesh. You can see the two layers in this photograph. Slope this layer down to the front of the tank.

However, back in the real world of modest-sized tanks in the living room, it is necessary to devise small practical filtration units for home use.

Filtration can be divided into three types - physical, biological and chemical. As the name suggests, physical filtration simply involves physically removing waste matter. This is the ideal method, but it usually only works with large granular matter, and would not work with, for instance, liquid waste. Biological filtration involves bacteria beds that 'biologically' consume waste matter, and this method of filtration is the basis of successful marine keeping. Chemical filtration involves chemically removing or absorbing waste matter, usually by means of an agent, such as activated carbon. An ideal marine system usually makes use of these three methods of filtration in combination.

Most marine systems are set up around an under gravel filter bed, the mechanics of which provide the necessary biological filtration. The complete system ideally consists of an under gravel filter plate that fits the entire base of the tank, covered by a Scam(2in) layer of coarse aggregate, such as coral gravel or dolomite chipping's, covered by further layer of coral sand, the two media being separated by a plastic mesh (called a 'gravel tidy') to prevent intermixing. Water is then drawn down through the media and up the uplift tube, either by means of an external air pump creating a rising column of bubbles, or more efficiently, by a water pump (a so-called 'power head') situated on top of the uplift tube. The nitrifying bacteria that flourish in the gravel and sand layers 'consume' the fishes' waste products and convert them topless harmful substances. In simple terms, nitrifying bacteria have a few basic needs in order to flourish - a surface on which to cling (the gravel/sand particles), plenty of oxygen (drawn from the well-oxygenated water flow), and a food supply (the nitrogenous waste products).

An efficient under gravel filter not only provides biological filtration,but also acts as a physical filter, as solid debris is drawn into and trapped by the coral sand. This can be a disadvantage, as the coral sand can get dirty and clogged. Although it is possible to add an outside canister filter in order to try and remove debris from the water flow before it clogs the sand, an alternative arrangement is to set up reverse-flow biological system. To do this, direct the water flow from the outlet pipe of a canister filter (containing physical and chemical filter media) into the uplift tube of the under gravel filter. In this way,cleaned water from the outside canister filter is forced underneath thunder filter plate and up through the layers of gravel and sand.This is far more efficient than the standard flow biological system, and can be recommended to beginners and more experienced autarkists.

It is worth mentioning trickle filtration here. An under gravel filter is quite 'wasteful' of resources, since nitrifying bacteria are naturally 'dry'

Reverse-flow under gravel filtration creatures, and when submerged, they drown and have to mutate constantly in order to survive and propagate. Trickle filter systems have the filter medium in small containers above the water and a trickle of water is passed over them. This system is far more effective in the sense that one small container of porous gravel can hold as many nitrifying bacteria as a large submerged filter bed, but its disadvantage is that only so much water can be passed over it before it becomes submerged.

There are several manufactured systems that incorporate trickle filter units, whether as separate components that you attach to your tank boras part of a complete built-in aquarium management system. Some aquarium set-ups combine both trickle filters and under gravel filters. Infarct, once you understand the fundamental principles involved, there is no reason why you should not build your own filtration system using both these methods.

The third part of the filtration jigsaw is chemical filtration. In order to supplement biological and physical filtration, many autarkists use activated charcoal and other proprietary filter media, usually placed Gina box or canister filter, which absorb waste products. Charcoal is particularly useful in absorbing phenols, which would otherwise tint the water yellow, but has the disadvantage of not being obvious when its useful life is over. Some proprietary filter media not only have much greater absorption capabilities than charcoal, but also indicate when they are spent by changing co lour.

A juvenile French angel (Penchant pare)from the Caribbean, one of the stunning marine fishes you can keep in a well set up aquarium. In most cases, the adult coloration outshines that of the juvenile, but with the French angel emotionalists prefer the dramatic yellow and black pattern of the youngsters. Small specimens about 5-7.5cm(2-3in) long are most often seen. The blue ring angel(P. annular is) is the cheapest of the available angels, especially as juveniles, and are often the first angels bought by beginners to the mariners hobby. As the yare both very hardy, this often works out well.

One disadvantage of absorbent materials, however, is that they also absorb copper compounds, which are a major ingredient in disease treatments, at least in a fish-only aquarium. An alternative method of chemical filtration is a piece of equipment called a protein skimmer, as lightly cumbersome unit that 'strips' the sea water of excess protein .Modern autarkists regard this as an essential addition to a system, its presence giving a stability previously unknown, but it is not always easy to find room for one, particularly since the top collecting cup has to sit just above the water level. For smaller tanks, inexpensive air-driven models are fine, but for larger tanks a more expensive motor driven unit is advisable.