Life support

Aquatic animal life support

Even if a public aquarium is able to use natural seawater because the facility is conveniently located on a body of water, there are many considerations and pieces of equipment that go into ensuring water is healthy for aquatic animals. We refer to an aquarium's plumbing and filtration all together as an animal's life support system.

Where does the water come from?

Public aquariums either have natural seawater or artificial seawater. Natural seawater seems like it would make the most sense if a facility is on a body of seawater, but there are some important things to consider when using natural seawater:

  • Cleanliness of the body of water, e.g. pollution, sewage
  • Levels of important or harmful compounds as compared to regular ocean conditions, e.g. necessary minor metals, unwanted metals
  • Changing conditions based on season or weather, e.g. salinity (salt content) in bays where rivers empty into or rainwater is often introduced

Typically, natural seawater is filtered as it is brought into the facility. Even if a facility is located on a suitable body of water, some choose to create their own in order to have more control over the water's makeup.

Artificial salt mixes are most often supplied by companies. (However, some facilities do make their own entirely from scratch!) Some companies target the aquarium hobby industry's smaller-scale use, while a few supply in bulk (like, we're talking 1-ton bags of salt). These salt mixes mimic the levels of major, minor, and trace elements found in favorable ocean conditions. The mix is stirred into freshwater (which is treated first to remove chlorine compounds) and voila—you've got seawater!

Introduction to filtration

Even if a facility uses a natural body of water to supply its aquariums, most modern aquarium systems are what we call closed or semi-closed, and utilize filtration equipment. Small, local facilities that only house native species might run open systems, where the natural source water goes into the aquarium and right back into the body of water.

This is a very quick overview on filtration categories; there's more information on filtration in a dedicated page you can also find later. Anyway, there are four general types of aquarium filtration:

  • Mechanical: removing particulates—catching visible particles
  • Chemical: removing dissolved compounds, through absorption or adsorption
  • Biological: cultivating bacteria to execute the nitrogen cycle
  • "Sterilization": killing microorganisms in a dedicated chamber

There are many different forms of equipment. However, an example of chemical filtration is a common piece of equipment found on saltwater systems called a foam fractionator.

The fractionator uses the chemical process called adsorption to remove tiny, tiny things from the water like proteins, fats, bacteria, and algae. Most commonly, a pump creates lots of fine bubbles that attract molecules and microbes to their surface due to the molecules' interactions with the surrounding water. (Hydrophilic and hydrophobic and other fun chemistry words like that.) The bubbles rise in a tower with things attached to them and spill over into a cup, which we take off to clean. On very large fractionators, the collection cup may have fancy, automatic rinsers!

See a foam fractionator (also called a protein skimmer, or just "skimmer") in action by dragging the slider!

Water quality testing

All this stuff about salt and equipment is great, but we don't just slap all of this together and hope for the best! Water is tested regularly for various things, from monthly to weekly to daily (to twice daily), depending on the system and what is being looked at.

Smaller organizations may use the same at-home water quality test kits that home aquarium owners use, while larger organizations most often have costly, high-tech laboratory equipment that provides more accurate results. At the largest public aquariums, there are staff members and volunteers dedicated to managing a laboratory that runs water quality for the entire facility.

There are many criteria that are important in water quality testing. The most common are:

  • Temperature
  • pH – how basic vs. acidic the water is
  • Salinity – salt content
  • Dissolved oxygen – how much oxygen is available for the animals to "breathe" (aquatic respiration)
  • Compounds in the nitrogen cycle – all animals excrete nitrogen-based waste (including us, in our urine!)

Other variables may be important to specific animal groups, corals being a common one that require additional tests to ensure water quality remains optimal.

Samples of aquarium water are typically collected using reusable plastic bottles, from which multiple tests can be run. These vials contain an ammonia test, where packets of chemicals were added to the water to turn it a certain color, and the water will be run through the machine (spectrophotometer) in the top left of the photo that determines the concentration of ammonia. (You can learn more about ammonia and the nitrogen cycle in Filtration!)
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