How much filtration do I need?
The purpose of the filter is to remove dirty materials from the aquarium. With so much material going through the filter, it is important to keep regular maintenance, as a neglected filter becomes a box of concentrated dirt through which all the aquarium water is passed. Also an impeller chamber can become clogged, and the fan will stop - hence no water will run.The general rule of thumb is that all the water in your tank should pass through the filter at least four times each hour. For example, a 150 litre aquarium requires a flow rate of at least 600 l/hr. If the filter choices are either 500 or 750 liters per hour, you should purchase the 750 liter one.
There are 3 main types of filtration:
- Mechanical filtration: Removes suspended materials from the water.
- Chemical filtration: Removes dissolved materials from the water.
- Biological filtration: Uses beneficial bacteria to convert toxic substances into relatively harmless ones.
Chemical filtration: The best material to remove dissolved solids is activated carbon. It has a large surface area, which readily soaks up dissolved minerals and chemicals. Carbon will also adsorb useful substances, such as medications, so it must be taken out when these chemicals are in use. After a period of time, the carbon becomes saturated and will no longer absorb chemical substances. When this happens it must be removed and replaced. In most filter systems, more than one medium is used so that mechanical and chemical filtration can occur simultaneously.
Biological filtration: Is the most important, because it uses the bacteria to change harmful fish waste products, ammonia and nitrite, into a less dangerous compound, nitrate. Biological filtration requires a "cycling" period while the bacteria establish themselves on the filter medium. This process can take up to 4-6 weeks, and requires ammonia for the bacteria to eat, which can be provided by adding one or two hardy, robust fish until the nitrite and ammonia levels are stable. Low-maintenance, in-tank, biological filtration can be used in all aquariums. For more information see my other guide about Cycling Your Aquarium.
How do I aerate my aquarium?
Power filters will do most of the oxygen enrichment in your aquarium as long there is sufficient agitation of the surface. Dissolved oxygen (O2) is created and carbon dioxide (CO2) is released via the surface area of your aquarium. The larger the surface area, the more O2 and CO2 will be exchanged. If you have a planted aquarium and a small fish population agitation is kept to the minimum to keep CO2 from escaping the surface.It is best that the air stone is used for visual aesthetics only as it isn't particularly useful for anything else. I don't use mechanical aeration as a personal choice as i find it can leave very tiny bubbles suspended in the water that results in a milky appearance to the water. An air pump itself provides aeration by compressed air moved by a diaphragm, which is electrically driven.
How big does my heater need to be?The strength of an aquarium heater is determined by its wattage. The larger an aquarium is the higher the wattage will be required.
The other main factor in choosing is the difference between the room temperature and the heat you would like the aquarium water to be. If your average air temp is 20deg. And you need your aquarium water at 25deg then the difference is 5deg. In a 200L tank the table below shows that a heater of 250Watt is required. As the temperature difference increases so to does the recommended heater wattage. The increase in wattage is not as steep in the larger aquariums due to the lower surface area to volume ratio conserving more heat.
Aquarium Volume 5ºC 10ºC 15ºC
20 Liters 25 Watt 50 Watt 75 Watt
40 Liters 50 watt 75 watt 100 watt
75 Liters 75 Watt 100 watt 150 Watt
150 Liters 200 Watt 150 Watt 200 Watt
200 Liters 250 watt 300 watt 2 x 200 watt
300 Liters 2 x 200 watt 2 x 250 watt 2 x 300 watt
This is just a guide as your own aquarium may vary somewhat. Factors such as lights and lids will impact on the heater strength required.