RATE OF FLOW: 

The amount of water that flows past a certain point within a specific time period. This is measured in gallons per minute (GPM).

 

REAGENT: 

Chemical indicators that used to test water chemistry in a swimming pool. These are the small bottles or tablets that come in testing kits.

 

RE-BAR: 

This is a bar used to add strength to concrete. Once an in-ground pool has been excavated, a steel cage made out of re-bar and a gunite shell is shot over and surrounding it. Re-Bar is short for "Reinforcement bar".

 

RESIDUAL: 

Refers to available chlorine levels remaining in a swimming pool after an initial treatment or after being exposed to contaminants.

 

RESTRICTED FLOW: 

When something is preventing the full flow of water. This can happen for any number of reasons such as full skimmer or strainer baskets, obstructions in the plumbing, dirty filter, undersized plumbing or equipment. It can also occur when devices like heaters, cleaners or fountains are placed in the circulation system. When the suction side has restriction it creates higher vacuum (or suction), while the pressure side creates higher pressure.