Aquatic Life Support Systems
A life support system refers to the physical structure used to contain water and house animals, as well at any ancillary equipment used to move and/or treat water. The type of life support system should be appropriate for the intended use. The selection and/or design of a life support system should be based on the natural habitat of the species, age/size of the species, number of animals maintained, availability and characteristics of the water required, and the type of research. The system must be constructed of nontoxic materials that do not leach toxicants or chemicals into the aquatic environment.
Recirculating systems are strongly preferred over static/renewal systems. If water is to be recirculated, the filtration components, and a sump or reservoir (area to collect water before and/or after treatment). Understanding the system’s component parts can help the user appreciate the basic design and how it may impact animal health and disease management.
Aquariums support a variety of life that require precise water quality and motion, lighting, and temperature regulation. There are three basic types of filtration: biologic, mechanical, and chemical. All recirculating systems have biologic and mechanical components, and most also include a chemical component. Some types of filters provide more than one of these functions and may be dual purposed in the design. Users should familiarize themselves with basic filtration and more complex system designs as their experience grows.
Biologic filters remove nitrogenous waste from the system. Biologic filters provide substrate and massive surface area for nitrifying bacteria to live. These bacteria are abundant in the environment and grow well when nitrogenous compounds (ammonia and nitrite) are present in the water column.
Mechanical filters are always placed before biologic filters in the system design. Mechanical filters typically receive water leaving the vessel housing animals and remove large particulate matter before water comes into contact with the biofilter. Mechanical filters can be as simple as floss or foam pads receiving a stream of water, or much more complex. Sand and bead filters are commonly used and have dual functions of mechanical and biologic filtration.
Chemical filters provide a way to treat the water. Activated carbon is very commonly used to remove toxins and colored compounds from aquarium water, which helps maintain clarity. Activated carbon filters may also be placed on inflowing water to remove chlorine and/or chloramine from city water. Activated carbon filters can also be used to remove treatment chemicals from water before discharge to city sewers. Other examples of chemical filters include protein skimmers and foam fractionators, which are commonly used in marine systems to remove proteinaceous waste (decreasing the load on the biofilter); ultraviolet light, which removes potentially pathogenic organisms from the water column; and ozone, which clarifies water and kills microbes.