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Aiming to share information and experience in fish keeping.



            A tank of rainbowfish with rocks, Java Fern and Java Moss



Setting up a Community Aquarium: Preparation


Types of filters

Air Pumps and Aeration


Adding Water


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Page 3 in this series: Plants, Lighting & An Example of a Planned Community Tank





SETTING UP A COMMUNITY TANK: an application of the previous data on Page 1.

A community tank is one that keeps mainly fish and has a few plants and rocks and other decorations.  The fish and plants may come from anywhere on Earth in a community tank- provided that they are compatible species. A Community tank is distinct from a biotype aquarium in which a specific environment is mimicked and is stocked with species particular to that biotype alone (e.g.  an Amazon biotype or a Lake Malawi biotype). Other specific, tank populations may comprise Livebearers Only, an Australian Rainbowfish collection (or single species) or be for a breeding colony of fish.

The first principles are the same for any tank design.  PLAN AHEAD & PREPARE for the type of aquarium that suits the type of fish or fishes that you wish to keep.

Ok, you have selected a suitable tank, washed it in clean water (no soap or detergent used) and have placed it in position on its polystyrene cushioning pad.  Now it can be fitted with filters and air-pumps and other equipment BEFORE the water is added.


 You cannot have too much filtration!  Begin with the best system that you can afford. There are three main filtering functions:

  1. particle filtration (also known as mechanical filtration) that removes large particles and suspended matter from the water.  Particle filtration improves the appearance of the tank but does not remove or control the dissolved substances that result from the natural metabolism of the fish.  With particle filtration alone, dissolved, toxic wastes build up in the tank and will harm the fish.
  2. biological filtration that uses naturally occurring bacteria to breakdown toxic, biological, waste products of the fish, including faeces, urine, ammonia (or ammonium in low pH  water) and nitrites. This uses a natural cycle- the Nitrogen Cycle-  to convert harmful ammonia and nitrites to less harmful nitrates. This is the most critical filtration type for the health of your fish.
  3. chemical filtration that uses adsorption and absorption  to remove harmful chemicals from the water. Activated carbon filter mediums and zeolite mediums are examples of chemical filtration. Chemical filtration is used to remove heavy metals and toxic wastes substances, including ammonia/ammonium (NH3/NH4), nitrite (NO2), nitrates (NO3) and phosphates.

All of these filtration functions are essential for good water quality. Most good filters combine all of these filtration functions in one unit.

All filtration processes must be supported by regular maintenance and partial water changes. As a general rule, aquarium water should be changed at the rate of 20% to 25% of the tank volume each fortnight. Never change ALL of the water at one time- unless you wish to recommence ageing the aquarium water! It is good practice to carry out any cleaning of filters when changing the water. Wash any dirty filter medium in the same water that you have syphoned out of the tank.  Dechloraminate the fresh water before adding it to your tank, of course.


Under gravel filters work well for beginners. They are simple to set up and run efficiently as combined particle and biological filters. U/G filters consist of special, perforated or slotted plates that sit on the bottom of the tank, directly on the glass. The plates are covered with a 2-3 cm layer of coarse gravel which acts as the filter medium. Connected to the plate is a riser tube that passes through the gravel and enables the water to be drawn upwards, creating a flow through the gravel, the plate and up the tube into the tank. The flow is driven by either of two methods; a) an air flow provided by bubbles from a small, plastic tube and an external air pump; b) an electrically driven, internally fitted pump with impellors that sits on top of the riser tube and draws water through the system. These filters work well, removing particles by trapping them in the sand where they decompose and are cycled by bacteria. New U/G filters take at least a month to become functioning, "cycled" biological filters. As the matured, U/G filter functions, the water chemistry changes as nitrates build up in the water. Over longer periods the water also tends to acidify. The gravel-bed also clogs up and can compact through long use. Cleaning the gravel bed and changing the water regularly is essential to keep the filter bed open and operating efficiently and to remove concentrations of nitrates. One disadvantage of U/G filters is that plants cannot be grown in the gravel beds- most plants roots are affected by the constant water flow. This problem can be overcome to some extent by having the bottom of the tank compartmentalised- one section for the filter and another for the plants- or by growing plants such as Java Fern (Microsorum pteropus), Dwarf Anubias (Anubias barteri nana), that do not require a root run in the gravel.

Internal filters, such as box filters (air-lift types or impellor-driven models) and sponge filters are also effective but they require more regular cleaning than U/G filters and can be noisy. Most require sponges and/or filter wool to function and allow for layering of filter media to provide different functions. The water passes through a particle removing stage first (through filter wool, Dacron pads of fine sponges) and a more open, biological filter stage provided by media such as coarse gravel, zeolite, sponges, ceramic tubes or bio-ball. Do not use fibre glass filter wool, as the fibres break and can enter the water and affect the gills of the fish. Activated charcoal or special filter media can be used as a second stage in box filters and need to be contained within the system by using fine-mesh bags. Dacron and nylon filter media are available and sheets can be cut to size to suit any filter. Internal filters need to be cleaned regularly and charcoal needs regular replacement.

External canister filters serve very well for larger tanks and also require regular maintenance. They allow for a variety of filter media to be used, in layered stages, including filter wool, sponges, charcoal, ceramic tubes, plastic bio-balls and zeolite. With proper installation, as a second-stage filter after the water has passed through a sponge layer to remove course particles, ceramic tubes and bio-balls are self-cleaning and provide very effective biological filtration. Charcoal and zeolite need replacing regularly and filter wool and sponges need to be washed frequently. External filters make this job easier than with internal filters- but it is still a necessary, messy business. If tt is done at the same time as a regular water change, the water removed from the tank can used to wash the filter media so that beneficial, bacteria cultures are not completely removed.  Never wash filter media in tap water unless it has been dechloraminated first.

Marineland's Bio-Wheel filters are excellent, combining particle, chemical and biological filtration in one external unit that hangs on the side of the tank. An electrically driven impellor draws water through a riser tube (J-tube) into the filter chamber where it passes through a fitted, filter pad that acts as a particle filter and as a chemical filter (it contains activated charcoal). At the out-flow point there is a padded bio-wheel that rotates in the emerging stream (like an old water-wheel in a waterfall), wetting its fins with water. The fins on the bio-wheel provide a surface on which denitrifying bacteria grow and provide an oxygen rich medium for biological filtration. Once "cycled", the filter and the wheel make an excellent filter system. The filter pads can be changed when required (or washed and re-used) and the bio-wheel requires no maintenance other than to see that it rotates freely on its bushes. The only disadvantage is that the returning water falls into the tank and can splash, be noisy or displace plants in the flow. Keeping the water level in the tank high, avoids those problems to some degree.

Choose the best filter that you can afford. Consult your local aquarium shop for advice on the range of types of filter available (it is huge- so do your research first) and check to see that your choice of type and size is adequate for the size tank, fish type and numbers that you keep. Aim for maintaining aquarium water with no nitrites or ammonia, as provided in a very efficient biological filtering system. 

Frequent, partial water changes are also essential as part of the water management routine, with fortnightly changes of 20% being minimal to remove the nitrates produced by the biological filter. 

A well functioning filtration system will take two to six months to mature the biological filtration component, depending on size and water flow rate and type of filter medium used.


Air pumps may be necessary for driving some air-lift filters and/or act as an aerator by providing bubbles of air to the water. What you need is a small air pump for aquarium use, a length of plastic tubing and fittings and an air-stone to provide the bubbles. The principle is simple: the fine bubbles produced by an air-stone effectively increase the surface area of the tank and enable gaseous exchange to take place between the water and the atmosphere, at a rate greater than allowed by the tank's water surface alone. In that way, a constant carbon dioxide level (at atmospheric levels) is available for plants and adequate oxygen is provided for the fish. Water movement and the small currents produced keep the water mixed, avoiding temperature layering as well. Any detritus is also circulated and made available for intake into filters.  For that reason, air-stones are placed near intake tubes for filters (unless they are part of the filter) so that detritus is removed.

You will need: an air pump, lengths of plastic tubing, an air-stone, gang valves or clamps and a check valve.

Why Aerate?

Since water temperature limits the amount of dissolved oxygen in the water, varying inversely with temperature, fish kept in water at or above 25oC are benefited by additional aeration. Oxygen dissolves in the water from two sources (mainly), from gaseous exchange at the surface and from release into the water from photosynthesising plants. Thus, in a well planted, adequately illuminated  aquarium, oxygen is made available to fish from the plants. It is the reverse at night, as plants take up oxygen and deprive the fish.  Hence aeration is required at night to allow gaseous exchange to keep oxygen levels at appropriate levels.  Aeration during the day keeps carbon dioxide at levels suitable for the plants and provides water movement.

Select a pump large enough for your needs and an air-stone that provides fine bubbles.  Allow 1 litre of air through the system per hour for every litre of air in the tank.  For a 55 litre tank, a pump that delivers at least a flow rate of 55 litres of air per hour. The range of pumps and air-stones available is huge so ask for advice.  Position the air-stone near the intake pipe for the filter.  Don't run it like a boiling pot but aim for a gentle flow.  Control is usually given by gang valves or clamps in the air line.

CARE must be taken with placement of the pump outside the tank so that water does not siphon out of the tank in the event of a back-flow caused by a power cut.  Check valves reduce the risk by preventing back flow.  If possible have the pump located above water level. Also ensure that electrical cables are safely away from the water.

ADDING SUBSTRATE, ROCKS and WOOD. Be environmentally conscious and do not plunder the landscape to obtain your sand, rocks and wood!
If an external filter is used, the gravel layers must be thin (no more than 30 - 50 mm) and regularly cleaned when siphoning out accumulated wastes.  The sand or gravel depth will need to be at least 20 mm in the front of the tank, grading to 50 mm at the back (with the slope providing a fall of the detritus to the front for easier cleaning later on). The darker the material, the better, as it reflects less light into the fish's eyes as they forage.  Most commercially available material in S. A. is too light in colour and needs to be shaded by plants and rocks. Shops usually sell what they can get, not what you need, and that is dictated by availability and commercial practices.  Do not use limestone, marl or dolomite gravels or sands. Choose quarried, alluvial quartz (this has rounded grains), river or creek sands and gravels that are not sharp or heavily mineralised with iron or calcium.  Again, consult your local supplier, who may stock a number of different substrate materials or obtain them for you on request. Wash the sand very thoroughly to remove any dust, silt, clay or humus particles that you have purchased as waste along with the substrate material.

Using an under gravel filter will decide the grain size used.  Fine, pea gravel is best for an under gravel filter, layered to a thickness of 50 to 80 mm.  Place the filtration grid on the bare, glass bottom of the tank and add the pre-washed gravel on top.  If cichlids are to be kept (or any species that digs) cover the first 40 cm layer of the sand with a fine mesh (sold as 'gravel bed keepers') and place the rest of the gravel over it.    

ROCKS (if used) also need to be smooth edged and of inert chemical composition.  Non-calcareous rocks are usually used (no limestone, dolomite or marl) in soft water, low pH environments. Sth Australia offers a nice range of local granite, basalt, slate, quartzite and sandstone that are suitable. Creek bed rocks may be suitable but please do not rob the environment to furnish your tanks- consult a landowner for permission to gather rocks. Make sure the rocks have no sharp edges and wash them thoroughly. Arrange the rocks so as they will not fall or move or create traps for the fish. Rocks are not essential to a tank, but are used for decor and to provide hiding places and territory markers for the fish in community tanks.

Limestone, dolomite and marble can be used in rock pile biotypes with Rift Valley cichlids such as mbuna where it is beneficial as calcareous rocks offer a buffering action that helps maintain pH around 8.2 - 8.5 (hard water, high pH environments) Aragonite is a superior buffer, however, and is found in coral gravel and sand and crushed oyster shells and is used in marine aquaria.

Always be mindful of potential falls when creating a rock pile biotype or any structures in the tank. Do not place rocks near unprotected glass heaters in case a fall cracks the glass. Place large, heavy rocks directly o to the bottom of the tank and not on the substrate, to avoid falls and shifting substrate.  Stack rocks carefully, so as they cannot move or fall. Cementing structures with silicone sealer is recommended when building hides and caves, for safety reasons. many fish species dig so ensure that rocks are immoveable.

 Go here for a detailed report on rock types for aquaria (link to an internal site).

WOOD can be used as decor for aquariums. Well seasoned mangrove roots, oak and beech logs and branches are good choices, however, S. A. offers little material that is suitable.  River Red Gum (Eucalyptus camaldulensis) wood, that has been long dead and well aged (seasoned), soaked and boiled, is suitable.  Imported peat "logs" and mangrove roots are available commercially and need to be well washed before using them. Using wood may stain the water with tannins and other dyes and also add to the acidity of the water (as in the Amazon itself!). Any strong discolouration may be removed by using an activated carbon-filter but this is not essential, as most fish thrive in such "black" waters.  Moulded plastic replications of aquatic landscapes are available from some aquarium shops and give a wood-like appearance, with low environmental impact.

Always treat any wood before using it, so that any tannins are removed from the timber.  Soak the wood in a large tub of water until it no longer discolours the water-this will take weeks!  Repeated soaking and boiling may make this job quicker, if practical, changing the water between successive soaking, boiling and cooling, until the water is not tainted.

Using painted stones or gravel, coral, shells or metal ornaments is risking trouble. Coral and shells trap food particles and pollute easily.  Processed items may contain heavy metals in the paint or ceramic fabric that may contaminate. Safe, moulded plastic aquarium decor is available from some aquarium shops- but check to see if it is labelled "safe". I prefer a "natural looking" tank environment and I do not use ornaments.  It is a not merely a matter of taste, as we can never be sure what paints and dyes have been used in colouring gravel, mouldings and coral.


Add the water slowly, so as not to dislodge the equipment, substrate, wood or rocks. It helps if a soup bowl or saucer is inverted and placed on top of the substrate onto which to gentle pour the water. Fill three-quarter way only at this stage, as it makes planting plants easier.


The best advice is to buy the biggest tank that you can afford (but no smaller than a 55 litre capacity) and at least 35cms deep. Fill with clean freshwater that has a pH between 7.0 and 7.5 (see below). I use dechloraminated tap water for general keeping, even in South Australia where water is notoriously hard.

Understanding Water Chemistry (this links to an external site): read this background material for an introduction to water chemistry.

Most South Australian tap water is hard and has a high pH and high conductivity because of its dissolved mineral content. Our River Murray water in S. A. is especially heavily laden with salts and pollutants. Most people will need to treat their tap water to make it suitable for fish that need soft water (such as Discus, Cardinal Tetras and Bolivian Butterfly Cichlids).

Fish require water that is pollutant free. This can be achieved by using dechloraminated tap water adjusted with additives that remove chlorine and/or chloramines. Chlorine or chloramine is added to the tap water by the Water Aurthorities to disinfect it for your health's sake but both chlorine and chloramine are poisonous to fish so must be removed from the water before using it in aquaria. Fortunately there are chemical preparations available that do this job instantly.

Dechloraminated Tap Water is made by treating tap water with Wardley's "Tri-Start" or Biotec's "Water Ager Cn" or similar products, to remove the chlorine and chloramines. Letting the water stand before using will remove free chlorine only. A serious aquarist will prepare a large volume of tap water by treating it to remove chlorine and chloramines and adjusting the pH and hardness to the correct levels before introducing it to an aquarium. Filtration through activated carbon will remove most other contaminants in tap water.  

Preparing water for use is advisable prior to using it for set up and later for water changes. Beginners should set up their tank and add the necessary dechloraminating mixtures before adding any fish. Remember to always dechloraminate any water before it is added to the tank at any time other than at the initial set up stage.

Adjusting pH is done quickly, by using chemical additives.  Sodium bicarbonate  (baking soda or bicarbonate of soda NOT baking powder) is used to adjust the pH upwards (above 7.0). Sodium bicarbonate does not act as a buffer to prevent further pH drop occurring as the water ages, however.  Tap water may contain a buffering agent that helps avoid  pH drop, otherwise buy a suitable alkaline buffer from your stockist and use that if the pH drops frequently. 

Reducing pH is not an easy matter, as water with a high pH is usually hard, high in alkalinity and well buffered (like SA's tap water).  Lowering the pH requires adjusting the  hardness and alkalinity levels first. Mixing water that has been softened by running it through a water softener could result in water with a desired pH.  Running peat in the filter will also lower pH (and colour the water like tea) and mixing pollutant -free rain water with hard tap water may reduce pH.  Adding phosphoric acid (food grade) also lowers the pH.  Add these chemicals in very small amounts over a period of several days and test the water frequently until the desired pH is reached.

Commercial products such as pH UP and pH Down are available from stockists. Purchase one that has a buffering characteristic, if your water supply is soft, to avoid rapid changes in pH. Using a good acid buffer is recommended for Amazon biotypes in areas where soft water does not come from the tap.  Consult your stockist.


  • NOW FOR THE NEXT PART- plants, lights and stock

    GO TO PART 3: plants, lights and stock Plants, Algae and New Aquaria: some facts Aquarium Lighting
    Setting up for Discus Setting up for keeping Siamese Fighters (Bettas) Setting up for keeping Lemon Cichlids

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    Watershed Aquaculture is now closed due to high costs of electricity in Sth Australia.

    Xena & Millie say, "Ooroo.
    Thanks for calling in."

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