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.

 

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.

 

PUMP: 

A mechanical wet-end, powered by an electric motor, which causes hydraulic flow and pressure for the circulation of the pool water.

 

PUMP STRAINER BASKET:

A device placed on the suction side of the pump, which contains a removable strainer basket designed to trap large debris in the water flow without causing restriction. Sometimes called a Pump Leaf Trap.

 

PUSH-PULL VALVE: 

A two position valve used for backwashing sand or DE filters.

 

PVC: 

Polyvinyl chloride, which is used to make flexible and rigid PVC pipe used for pool plumbing.