Pond Terms Definitions

Aeration: Adding oxygen to water by bringing air into contact with the water.

Aerobic: Relating to or caused by the absence of oxygen. (For living things: needing oxygen to be active or living.)

Algae: Members of several phyla of the kingdom called Protista. Although algae have much in common with plants, they also have many differences. Algae members include the common nuisance algae of ponds - microalgae, hair algae and slime algae.

Alkalinity: The total concentration of alkaline substances in the water expressed as equivalent calcium carbonate. In fresh water, alkalinity and hardness are usually similar because most of the alkalinity normally comes from calcium and magnesium carbonates.

Amphibian: A member of the class of animals that includes frogs, toads, newts and salamanders.

Ammonia: A compound of nitrogen and hydrogen which is highly soluble in water and is toxic to fish at extremely low concentrations. Decaying organic matter (e.g. leaves, algae, fish excrement) produces ammonia in ponds. 

Anaerobic: Relating to or caused by the absence of oxygen. (For living things: able to live in an environment which has no free oxygen.)

Aquaculture: The growing of animals and crops in water (underwater farming).

Aquaponics: The combination of hydroponics and aquaculture. Fish are fed in tanks and the water is circulated through a hydroponic system to supply nutrients to the plants in the form of fish excretions (fish fertilizer). The plants absorb the nutrients (nitrates in particular) and the purified water is then circulated back to the fish.

Blanket weed:  see hair algae.

Biological filter: Any surface which harbours nitrifying bacteria.

Denitrifying bacteria: Bacteria which convert nitrate to nitrogen  (some aquaculture engineers mistakenly use this term when they are talking about nitrifying bacteria).

Dissolved oxygen: Oxygen dissolved in water making it available for respiration for underwater organisms (e.g. through the gills of fish).

Ecosystem: A community of interacting organisms together with the environment with which they also interact (e.g. a pond).

Free ammonia: That part of the ammonia in water which is not bound up as harmless ammonium ion. ("Free" ammonia and ammonium ions exist in an equilibrium which varies with changes in the water's temperature and pH. It is the free ammonia which is highly toxic to fish.)

Genera: Plural of "genus", a term which classifies a group of closely related species.

Green water: Water turned green by microalgae.

Hair algae: A common name for several closely related genera of filamentous green algae. (Also called string algae and blanket weed. In fresh water, the common genera are Spirogyra, Mougeotia and Zygnema.)

Hardness: The amount of dissolved minerals in water. In fresh water, hardness usually consists mainly of the total amount of calcium and magnesium dissolved in the water. It is expressed as milligrams per litre of equivalent calcium carbonate.

Head: The height above the pond's surface to which a pump delivers water.

Heavy metal: A metal with a density greater than five times that of water. The term includes iron, copper, zinc, cadmium, mercury and lead. Heavy metals can accumulate in animal tissues, including those of fish, until they reach toxic levels.

Impellor: The part of a pump which pushes water through the pump housing.

Kingdom: One of the major groups of organisms into which living things are classified.

Liner: Any waterproof material used to line a pond.

Magnetic drive pump: A pump which operates by using an electromagnet to turn the pump's impellor instead of using a drive shaft. (The advantage of this type of pump is that there are no moving parts between the motor and the impellor so the pump lasts much longer than other pumps.)

Maximum water flow: The flow a pump gives when the water's head is zero.

Mechanical filter: Any filter which physically removes suspended particles from water.

Microalgae: Microscopic forms of algae (including the algae that cause "green water" in ponds.)

Nitrate: A compound of nitrogen and hydrogen which is highly soluble in water and is toxic to fish only at fairly high concentrations. (Nitrates are produced in ponds by nitrifying bacteria (Nitrobacter) converting nitrite.)

Nitrifying bacteria: Bacteria which convert ammonia to nitrite and nitrite to nitrate.

Nitrite: A compound of nitrogen and hydrogen which is highly soluble in water and is toxic to fish at low concentrations. (Nitrite is produced in ponds by nitrifying bacteria (Nitrosomonas) converting ammonia.)

Nitrobacter bacteria: The genus of bacteria which converts nitrite to nitrate.

Nitrosomonas bacteria: The genus of bacteria which converts ammonia to nitrite.

pH: A measure of the acidity or alkalinity of water. pH ranges from 0 to 14, with 7 being neutral.  Below 7, acidity increases exponentially and above 7, alkalinity increases exponentially.

Phosphate: A compound of phosphorus and oxygen which is readily taken up by algae and plants.

Phosphorus: An essential element for animal, plant and algae growth.

Photosynthesis: The making of organic matter by plants, algae and certain other organisms by using sunlight, carbon dioxide, water and inorganic salts (including phosphorus).

Phyla: Plural of the word phylum which is a division of one of the kingdoms into which life is classified.
 
Polyethylene: A type of plastic.

Pressure filter: A mechanical and/or biological filter through which water flows under pressure.

Protista: One of the kingdoms of living things. It includes algae, amoebas, ciliates, slime moulds, water moulds and a number of other forms of life.

Slime algae: Various forms of algae which cover pond walls, plants and water features. (As their name suggests, the algae are soft and slimy making them difficult to remove by hand.)

String algae: See hair algae.

Submersible: Able to operate underwater.

Ultraviolet clarifier: A container enclosing a globe which emits ultraviolet light. (The ultraviolet light kills algae in any water which flows through the container.)

Vortex filter: A mechanical filter that uses centrifugal force to "throw" suspended particles out of the water.

Water Garden: A garden containing water features and/or ponds.

Water quality: The physical, chemical and biological characteristics of water.

Waterwall: Any wall down which water flows.

Waterwall trough: The water container at the top of the waterwall. (Water is pumped to the trough which distributes it so it flows back to the pond as a falling sheet or by trickling down  the wall.)

Zeolite: A naturally occurring clay which adsorbs ammonia from water.