A I B I Bre I C I Chl I Cya I D I E I F I Flo I G I H I I I J 

L I M I N I O I P I Q I R I S I Sta I T I U I V I Vol I W I Z

O-RING: A loop of elastomer in a round "O" shape that is used as a mechanical seal or gasket. They fit in a groove and are compressed during the assembly of two or more parts, which creates a seal at the interface.

OTO:  A way to test for free available chlorine levels in a swimming pool. Usually comes in the form of a test kit.

OXIDATION:  The "burning up" of organic waste and compounds in the pool water. It also refers to what you may see on your metal pool surfaces if your water is corrosive. Rust is a form of this kind of oxidation.

OZONE:  The molecule containing three atoms of oxygen; known to be a very powerful sanitizer. Ozone producing equipment creates this molecule by UV radiation or corona discharge generators. 

pH:  The scale of relative acidity or alkalinity, expressed in logarithmic numbers from 0 - 14, with 7.0 being neutral. What's really being measured is the hydrogen ion concentration. Some would say pH stands for Power of Hydrogen.
 

PLASTER:  A common type of interior finish applied over the concrete shell of an in-ground swimming pool.
 

PLUMBER'S SNAKE: Sometimes known as a "toilet jack," is a flexible auger used to remove clogs in plumbing that cannot be loosened with a plunger. Most devices consist of a coiled metal wire with space between the coils at the end. The other end is attached to a device with a crank that rotates the wire as it moves down into the pipe. Drains are cleared by one of several mechanisms:

• The auger end of the wire digs itself into the clog much like a corkscrew, allowing retrieval of the object causing the clog when the snake is pulled out. (Commonly hair, combs, small toys, cloth.)

  The end of the snake breaks up the object, allowing it to pass through the drain. (Commonly tree roots, foam insulation, plastic objects.)

• The snake flails around the inside surface of the pipe, scraping off accumulated matter (ranging from mineral deposits to bacon fat) which was reducing the effective interior diameter of the drain pipe.

The auger should be turned clockwise only, unless it has become jammed in the drain. Not only is this essential for retrieval of foreign objects, but for the longevity of the cable.

PLUNGER:  The sliding disc assembly that changes valve position in a push-pull valve. For example; up for backwash, down for filtration.  

POTASSIUM PERMONOSULFATE:  See non-chlorine shock.

POLYMER:  An algaecide / algaestat made up of repeating polymer molecules. Used for green algae and available in varying strengths.

PPM:  Parts per million. A method of assigning value to certain concentrations of chemicals in the water. For example, alkalinity should be kept at 80-120 parts per million, by weight and in relation to the water it's dissolved in.

PRECIPITATION:  To precipitate is to come out of solution; become insoluble by result of chemical action. Material forced out of solution, purposefully or accidentally, will then settle, stain or scale, or remain suspended in the water.

PRESSURE CHECK:  A test for the rate of water flow; also a test for leaks in plumbing by placing a line in question under pressure and waiting for the pressure to drop.

PRESSURE GAUGE:  A device indicating pressure in a filter system. Provides a determination of how the system is operating, and informs us when service is required.

PRESSURE SIDE:  The return side of the plumbing. The section from the pump impeller towards the pool.  

PRESSURE SWITCH:  A switch used in pool heaters which opens when the flow rate is insufficient for safe heater operation. This disrupts the circuit in the heater, preventing it from firing.