Pool Terminology Glossary

A

Alkalinity (Total Alkalinity)

Measure of water's ability to resist pH changes. Ideal range: 80-120 ppm. Acts as a pH buffer to prevent rapid pH swings.

Algae

Microscopic aquatic organisms that grow in pools. Types include green, yellow (mustard), and black algae. Prevented by proper sanitizer levels and regular brushing.

Algaecide

Chemical used to prevent or kill algae growth. Not a substitute for chlorine. Commonly used as preventive measure or winter treatment.

B - C

Backwash

Process of reversing water flow through filter to clean out trapped debris. Performed when pressure gauge reads 8-10 psi above clean pressure.

Bromine

Alternative sanitizer to chlorine, often used in hot tubs. More stable at high temperatures.

Calcium Hardness

Measure of dissolved calcium in water. Ideal range: 200-400 ppm. Too low causes corrosion; too high causes scaling and cloudy water.

Chlorine (Free Chlorine)

Primary sanitizer that kills bacteria and algae. Ideal range: 1-3 ppm for pools, 3-5 ppm for hot tubs. "Free" chlorine is active/available chlorine.

Combined Chlorine (Chloramines)

Spent chlorine that has bonded with contaminants. Causes "chlorine smell" and eye irritation. Should be kept below 0.2 ppm. Remove by shocking.

CYA (Cyanuric Acid)

Chlorine stabilizer that protects chlorine from UV degradation. Ideal range: 30-50 ppm. Too high reduces chlorine effectiveness; too low causes rapid chlorine loss.

D - G

DE Filter (Diatomaceous Earth)

Filter type using fossilized diatoms as filter medium. Filters down to 3-5 microns. Most effective filtration but requires more maintenance.

GPM (Gallons Per Minute)

Measure of water flow rate through pump and filter system.

GPH (Gallons Per Hour)

Alternative measure of flow rate. GPM × 60 = GPH.

H - M

Muriatic Acid (Hydrochloric Acid)

Strong acid used to lower pH and alkalinity. Typically 31.45% concentration. Always add acid to water, never water to acid.

Oxidizer

Chemical that breaks down organic contaminants. Chlorine and non-chlorine shock are oxidizers.

P

pH

Measure of water acidity/alkalinity on scale of 0-14. Ideal range: 7.2-7.6. Below 7 is acidic, above 7 is basic. Affects chlorine effectiveness and swimmer comfort.

ppm (Parts Per Million)

Standard measurement unit for chemical concentrations in pool water. 1 ppm = 1 mg per liter of water.

Prime (Priming the Pump)

Filling pump with water before starting to prevent dry running and damage.

S

Salt Water Chlorine Generator (SWCG)

Device that converts dissolved salt into chlorine through electrolysis. Typical salt level: 2700-3400 ppm.

Sanitizer

Chemical that kills bacteria and algae. Chlorine and bromine are common sanitizers.

Shock (Superchlorination)

Process of adding large dose of oxidizer to eliminate contaminants and chloramines. Typically 2-3x normal chlorine level. Perform weekly or after heavy pool use.

Skimmer

Opening in pool wall that draws surface water into filter system. Removes floating debris like leaves and insects.

Stabilizer

See CYA (Cyanuric Acid). Protects chlorine from UV sunlight degradation.

T - Z

TDS (Total Dissolved Solids)

Sum of all dissolved substances in water. High TDS (>2000 ppm above fill water) may require partial drain.

Total Chlorine

Sum of free chlorine plus combined chlorine. Total - Free = Combined chlorine.

Turnover Rate

Time required for entire pool volume to pass through filter system. Recommended: Complete turnover every 8-12 hours.

Vacuum (Pool Vacuum)

Device for cleaning pool floor and walls. Types include manual, automatic, and robotic.

Common Abbreviations