• Basic equipment

    If you want to set up a marine water aquarium, you first need some good quality equipment. The most important is:


Equipment space area
Ideally the equipment will be located in an area beneath the aquarium, in the aquarium furniture. Here you will need sufficient space for the filter tank (known as the “filter sump”) with skimmers, filters, feed pumps, osmosis store, automatic top-up, power supply and gauges/adjusters etc. as necessary. Tubes and pipe work must therefore pass through the base of the aquarium.

If you opt for an EHEIM marine water aquarium combination you will have the complete basics, including filter tank, pre-installed pipes etc.

Filter tank
The filter tank (“filter sump”) is a specialised tank in the bottom cabinet. It should consist of a number of chambers, including:
• Intake chamber – this is where the skimmer is located and where the water from the aquarium enters

• Filtration chamber – this is where filter mats (in the role of a internal filter, for example) or if required, fitted external filters, assume the task of filtration

• Collection chamber (or clear water chamber) – this is where the return pump is located which feeds the purified water back into the aquarium

• Plus, if required, an evaporated water storage chamber for revers osmosis water (freshwater without any salt!) – if necessary with auto matic top-up

Protein skimmer
The skimmer is the main filter in a marine water aquarium. This is used to immediately remove waste products (excreta from fish and other animals in the form of ammonium/ammonia, proteins etc.), from the water before they oxidise and form toxic end-products such as nitrate and phosphate.

The skimmer typically works by producing bubbles of air to which molecules of protein remain attached by electrostatic attraction. Turbulence creates a firm brown foam (flotation) which is fed into a collection container, where it can be disposed of.

There are various methods of producing foam. The EHEIM SKIMmarine 800 skimmer makes particularly effective, quiet and energy-saving use of a new type of needle-wheel design and venturi unit.


Mechanical filter (if required with auxiliary filter)
In an ideal situation, the protein skimmer and a mechanical internal filter will suffice as filters in a marine water system, which has been run in and looked after properly, in particular to hold back particles of dirt. The task of biological filtration is largely assumed by the organisms in the aquarium.

In order to attain the optimum water values – especially in the run-in phase – further filtration may be necessary, including, for example, biological filtration to break down any harmful chemicals and active carbon filtration to eliminate what is known CDOM (yellow coloured dissolved organic matter).

Use a suitable EHEIM external filter, which can be fitted with a variety of filter media (only peat is taboo!).

Return pump
In order to return the clean water from the collection chamber in the filter tank back into the aquarium, you will need a return pump, unless the water is pumped into the aquarium using a different piece of equipment (e.g an external filter).

Some EHEIM marine water aquarium combinations are already fitted with a suitable pump.

Circulation pumps
In a marine water aquarium the current is absolutely essential. It distributes temperature, gases, particles of food, it raises the oxygen content, nurtures growth in colonies of coral, removes metabolic waste, prevents films of scum from forming (from deposits) on the surface of the water and reduces the pH value and disease.

A high rate of flow is important so the circulation should be about ten times the volume of the tank per hour (3000 litres per hour in the case of a 300 litre aquarium). Even so, only minimal flow should touch the animals and for that reason the jet of water must fan out over a wide area.

EHEIM streamON circulation pumps meet all the requirements as they ensure optimum circulation of water and a natural, gentle current.

Reverse osmosis system
The ecosystem in a marine water aquarium is highly sensitive and for that reason it requires particularly pure water. A reverse-osmosis system is therefore part of the basic equipment.

Reverse osmosis is a natural, purely physical process of filtering salts and harmful chemicals out of tap-water. It forces the water through a membrane which has such fine pores that it only lets molecules of water through. Most of the substances that are dissolved in tapwater are unable to penetrate the membrane and so ultra-pure water is created.

There is a wide range of reverse-osmosis systems – from small units which are connected direct to the tap, to more complex installations with additional filtration. For the beginners point of entry, a small system with a pre-filter and membrane will suffice.


Automatic top-up
Water is always evaporating, especially in open aquariums. In closed tanks too, water is lost because of the flow (circulation pump) and also from the filter tank (skimmer). In a marine water aquarium the loss of water can have fatal consequences because it will concentrate the salt content (increased density), increase  the amount of harmful chemicals and organic impurities and make any life impossible.

With an automatic top-up you will be able  to maintain constant water levels at all times (even when you are on holiday). A sensor monitors the level and a dosing pump makes up the shortage of water by feeding fresh-water (e.g. from the revers osmosis water storage chamber) into the aquarium.


The salt content in a coral reef aquarium must be between 3.4 and 3.57 % and should be measured and adjusted on a regular basis. In the case of a partial water change in particular, the water value must be exactly the same as the aquarium water. The commonest form of gauge is a hydrometer which measures the weight of the water per litre at 25 °C. As salt has a weight of its own, water will weigh more as the salt content increases. Water temperature also has an effect on the weight, it is therefore usual to calibrate the equipment at 25 °C.

One alternative is the refractometer, which works on the basis of the difference in the refraction of light in distilled water and water which contains salt.


Heating (Cooling)
The temperature in the tropical marine aquarium must be between 24 and 26 °C. Only a few degrees above or below can disrupt the balance and endanger the life of corals and other occupants.

You can adjust the EHEIM thermo controlled heaters accurately between 18 and 34 °C. They will maintain the specified temperature at a constant level, are fully submersible and can be fixed in place in the aquarium (or in the filter tank) simply by using suction cups The heaters are available in various sizes for aquariums between 20 and 1000 litres.

For cooling – possibly on particularly hot summer days – it is best to place a ventilator on the open aquarium or purchase a specialised cooling device.