P

PALUDARIUM

An aquarium that is set up with a dry land area as well as a water area.

PAPILLA

A tube descending from the abdomen of male fish used to fertilize eggs. It is typically only visible during breeding. See Milt.

PARTICULATE

Nutrients that can cause explosive growth of algae in the marine environment.   Although essential for algae growth, limiting is necessary in a closed aquarium.

PARTS PER MILLION (PPM)

PARTS PER THOUSAND (PPT)

PECTORAL FINS

Paired fins, one on each side of the body located behind the gill covers. They are often used for more precise maneuvering. In a few species they are used for propulsion.

PELVIC FIN

Paired fins towards the underside of the fish. Vary in size and shape greatly. In anabantids often elongated. Appear to function as ‘brakes’ especially for species which move in a start/stop motion.

PFO

Manufacturer of lighting systems.

A compound introduced into the aquarium through organic or inorganic means that promotes excessive algae growth. Can be removed through water changes.  

PHOTO PERIOD

The amount of time the lights are on, the length of a day.

PHOTOSYNTHETIC ORGANISM

Any animal that uses photosynthesis to produce food and energy.

PISCIVORE

One that eats fish.

PLANKTER

Singular of Plankton

PLANKTON

A complex mixture composed of the larvae of fish, corals and other invertebrates, algae, and numerous single cell organisms.  It is a universal food source for the creatures of the deep.

PHYTOPLANKTON

ZOOPLANKTON

PLENUM

A space between the aquarium bottom and substrate, created by supporting the substrate above the bottom using UGF plates or some other support structure. Used to keep Nitrate levels low in a saltwater aquarium. Water and organic waste diffuses down into the plenum where the wastes concentrate. Nitrifying bacteria in the upper levels of the substrate use the oxygen and produce nitrate in the water as it moves down into the space. Denitrifying bacteria living in the oxygen-poor lower levels of the substrate slowly convert Nitrate into harmless nitrogen gas.

POLYVINYL CHLORIDE (PVC)

Used for piping / plumbing

POTASSIUM IODIDE (KI)

POWDER BLUE TANG (PBT)

POWER COMPACT (PC)

A fluorescent light. See Metal Halide (MH), Very High Output (VHO), Normal Output (NO)

POWER HEAD (PH)

A small submersible electric pump.

POWERS OF HYDROGEN (pH)

Measurement of the degree of water acidity. It is determined by the amount of acids and bases in the water. If the amounts are equal it is called neutral with a number rating of 7.0. If more acids it is called acidic with number rating of less than 7.0, if more base it is called alkaline with a number rating of more than 7.0.

PROTEIN SKIMMER

Used in saltwater tanks to remove organic pollutants from the water before they break down. Also called Foam Fractionator. Produces tiny air bubbles which attract and hold pollutants, which are then deposited into a separate container.

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