Acidic - having a pH value less than 7

Activated carbon - carbon material that is used in the purification of water. Activated carbon is very porous with a large surface area for absorbing contaminants. Also used to remove chlorine.

Aeration Pump - pump designed to pull air from the atmosphere and inject it into the water

Algae - microscopic organisms that share  characteristics with other plants, however, lacking stems, roots, and do not flower; common forms are single-celled 'green water' algae and a multi-celled 'string' algae

Algaecide - chemical that controls or stops the growth of various algae

Alkaline - a pH value greater than 7 .0

Ammonia - NH3 - colorless, odorless form of nitrogen that is toxic to pond fish; produced from decaying organic matter, is present in fish wastes, and excreted from fish gills; test levels should be zero.

Anchor worms - a type of crustacean, that is commonly attached to the base of fins; appears as a thin whitish "worm" that is embedded in the skin of the fish

Bacteria - single celled microscopic organisms that lack a nucleus. There are many types of bacteria, both good and bad

Ballast - electrical supply for some lights, such as an ultraviolet light. Used to regulate electrical current

Ball valve - used to regulate water flow through a pipe. It allows for complete flow when fully open.

Barb - plumbing fitting with ridges that accepts equal size vinyl tubing

Barbels - koi possess two pairs of barbels; used to locate food by taste. The whisker-like barbels are located near the mouth

Bare root - plants with the soil removed from their roots; this is the way we ship our plants and they are ready for potting

Biological filter - filters that house media for nitrogen-consuming bacteria to live on and colonize

Bog - wetland ecosystem

Bottom Drain - installed in the pond bottom; uses a water-tight fitting to go through the liner. Bottom drains can be used as a continuous intake for the pump and filtration system or only used to occasionally flush debris from the pond.

Buffer - substance dissolved in the water that helps stabilize pH

Bulkhead - special plastic fitting to provide a watertight seal through a plastic container or a flexible pond liner.

Caudal fin - tail fin of a fish

Check valve - used to provide flow through a pipe in one direction only. When installed between an external filter and the pond, it keeps the dirty water in the filter from flowing back into the pond if power is lost. They are also used to keep an external pump primed if power is lost. Spring type check valves should never be used in a pond installation. AKA: Foot Valve

Chloramines - chemical that is sometimes present in municipal water supplies and is poisonous to fish; unlike chlorine, it will not evaporate from the water

Chlorine - chemical this is commonly used in municipal water supplies and is poisonous to fish; will evaporate if given enough time

Cold-blooded - having a body temperature that is regulated by the environment

Decomposition - breakdown of matter by bacteria and fungi

De-Icer - unit placed in the pond to maintain a hole in the ice that forms on the pond surface

Direct Drive Pump - pump whose impeller is connected directly to the motor

Disappearing fountain - a water feature consisting of a fountain with no open water; the water spills from the fountain into an underground basin where it is recirculated back through the fountain

Dorsal fin - fin located on the back of fish

Ecosystem - self-supporting community in which living and non-living things interact

Enzyme - protein that helps speed up a chemical reaction such as the breakdown of organic debris

EPDM - ethylene propylene diene monomer; the material from which most flexible pond liner is made

External Pump - water pump that sits outside the water with an intake line going into the pond or skimmer. AKA In-line pump

Filter - unit designed to clean and clear the water

Filter Media - the material in a filter that either traps debris in a mechanical filter or provides surface for beneficial bacteria in a biological filter. Most media can function as either, at least to a certain degree

Fin rot - bacterial disease; fins become cloudy then turn white, followed by filaments separating, becoming frayed, and then starts to disintegrate; progresses from tip toward the body; blood streaks may appear throughout the fins

Fish lice - free swimming circular parasite; semi-transparent or brownish in color; wounds are spherical and often inflamed and swollen

Flex PVC - flexible version of PVC (polyvinyl chloride); this pipe uses the same fittings as standard schedule 40 rigid PVC.

Flocculent - treatment that causes suspended organics to clump, which then will sink to the pond bottom

Foot valve - used to provide flow through a pipe in one direction only. When installed between an external filter and the pond, it keeps the dirty water in the filter from flowing back into the pond if power is lost. They are also used to keep an external pump primed if power is lost. Spring type foot valves should never be used in a pond installation. AKA: Check Valve

Fountain - there are various definitions of a fountain; It can be a broad water feature where the water movement is the main focus. It can also be the specific part of the feature that is the moving water such as a spray of water or a spitting statue.

Fungus - organism that feeds by absorbing nutrient through its outer cells; some types will grow on fish, commonly appearing as cotton-like growth

Gallons per hour - GPH - unit used to measure water flow

Gate Valve - for fully opened or closed operation. They are not used for regulating flow. AKA: Knife Valve

GH - general hardness; measurement of Calcium and Magnesium

Gills - fleshy, highly vascular organs comparable to lungs used in aquatic respiration

Hardiness - the ability of a plant to withstand winter cold

Hardness - quality of water mostly caused by excess Calcium and Magnesium

Hardy - plant that can survive winter temperatures (note this depends on the extremity of the temperatures)

Head pressure - the total of static head, friction head, and pressure head; used to size the pump of a pond

Invasive - plants that spread out of control; one characteristic of a weed. Many are banned in certain states due to their aggressive nature.

KH - carbonate hardness; the measurement of carbonate and bi-carbonate in the water.

Kilowatt - KW - electrical unit of power equal to 1000 watts or 1.341 horsepower

Kilowatt-hour - KWH - basic unit of electrical energy that equals one kilowatt of power applied for one hour

Knife valve - for fully opened or closed operation. They are not used for regulating flow. AKA: Gate Valve

Koi Pond - water feature which has the main focus of koi; Koi ponds typically have few if any plants. They are deeper than most water gardens and should have much greater filtration

Lateral line - series of sensory pores opening to the exterior along the side of a fish

Magnetic Drive Pump - pumps whose impeller is not connected directly to the motor. Instead the motor and impeller are each connected to magnets. As the motor spins its magnet, the other magnet spins which causes the impeller to turn.

Mechanical filter - unit that mechanically removes particles from the water (physically traps particles)

MPT - male pipe thread; connection type using male (outside) threads

Nitrate - NO3 -form of nitrogen; product of nitrification by beneficial bacteria, less toxic than other forms of nitrogen, used by plants

Nitrite - NO2 - toxic form of nitrogen; product of nitrification by beneficial bacteria

Operculum - the gill cover of a fish

pH - measure of the hydrogen ion concentration of the water, and therefore of its acidity or alkalinity; pH of 7 is neutral; above 7 is alkaline; below 7 is acidic

Parasite - an organism that lives by feeding off of other host organisms

Pathogen - any organism that causes disease

Pectoral fin - the front paired fins used to control delicate movements

Pelvic or Ventral fin - posterior paired fins, located in the abdominal position or towards the rear

Perennial - any plant that lives more than 3 years

Phytofilter - natural filtration using plants; plants have a natural ability of removing nutrient and toxins.

Pondless or Disappearing waterfall - a water feature consisting of a waterfall only, no open water; the waterfall falls into an underground basin that houses the bulk of the system's water

Pond Liner - the flexible material that forms the waterproofing barrier between the water and the excavation below.

Pot bound - plant growing in a pot that is too small to allow proper leaf and stem growth

Prefilter - mechanical filter placed before the pump inlet; helps to minimize clogging of the pump

Pressure head - additional pressure required by some filters, venturis, and other devices; most pond builders can ignore this

Pressurized filter - a filter that is completely enclosed; this allows the filter to act as an extension of the plumbing and so does not have to be placed at water level or at the head of the waterfall, can be located at any elevation

Pseudomonas - gram-negative bacteria found in water; aids in organic decomposition but also causes infections in fish

Reservoir - body of water collected and stored usually at the head of the waterfall or stream

Rhizome - in-ground plant stem from which roots and shoots form

Root bound - growing a plant in the same container too long forcing the roots to become tangled and grow in circles; roots must be carefully loosened when repotted

Runoff - water that flows over the ground and reaches a stream or pond as a result of rainfall; best to divert runoff so it does not go into the pond

Salinity - amount of salt dissolved in a given volume of water

Skimmer - unit that skims debris off of the pond surface; functions as a mechanical pre-filter. These are usually installed outside the pond and house the pump.

Sludge - muck settling in the pond bottom or trapped in filters; made up of many organic debris including fish waste, partially decomposing plant material, etc.

Static head - vertical distance you raise the water above the pond surface

Stream - flow of water, typically with less than a 45 degree slope.

Submersible Pump - water pump that sits in water at all times

Trace elements - chemicals that are needed in small amounts by pond organisms to grow optimally

Transformer - device that converts electrical current. Typically these convert household 115volt electricity to 12volt for pond lighting

Tuber - underground storage organ; can be either part of the stem or the root

Ultraviolet sterilizer - a device that uses ultraviolet light to kill free-floating algae, bacteria, and other tiny organisms

Underlayment - geo-textile material placed beneath pond liner to protect the liner from puncture

Union - plumbing fitting used for disconnecting purposes, the fitting couples 2 sections of PVC together and then can be unthreaded to disconnect. Often used on external pond equipment to have the ability to remove without cutting the pipe.

Up-Flow Filter - filter in which the water enters at the bottom then flows up through filter media before exiting the filter.

Variegated - blotched, edged, or striped with yellow, white, or a cream color; as in Variegated Sweet flag

Venturi - type of valve used for aerating ponds; draws air into quickly flowing water adding bubbles to pond

Watercourse - flow of water, typically with less than a 45 degree slope.

Waterfall - vertical drop of water

Waterfall Tank - a basin that fills and overflows with water creating a waterfall; these are often biological filters as well, but not by definition

Waterfall Well - unit that sits in a pondless or disappearing waterfall basin to house the pump and maintain water volume for circulation.

Water Garden - water feature with focus on plants, but may also contain fish (primarily goldfish)

Weir - technically a dam; the term is used to refer to the spillway of a waterfall or the opening on a pond skimmer.