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Pool Chemical Glossary

Decoding Pool Chemicals: Your Comprehensive Glossary

Navigating the world of pool chemicals can be confusing, especially if you're new to pool maintenance. That's why we've created this all-inclusive glossary to help you understand the key chemicals and terms you'll encounter. This guide aims to demystify the science behind keeping your pool clean, clear, and safe for everyone.

Acid Requirement:

This term refers to the amount of acid, or pH reducer, needed to balance the water's acidity and alkalinity levels.


These are microscopic plants that can thrive in your pool, particularly in warm conditions. Algae can be green, brown, or even black, and they can discolor your pool water.


These are specialized chemicals designed to eliminate algae and prevent future growth.


This is the measure of minerals in the water that counteract acidity, essentially the opposite of acid on the pH scale.


These are microscopic organisms that can potentially cause illnesses and should be effectively eliminated from pool water.

Metal Sequestrants:

These chemicals bind with dissolved metals in the water to prevent staining and discoloration.


These are byproducts formed when chlorine reacts with impurities. They are less effective as disinfectants and can cause eye irritation and a chlorine-like smell.


This is the most widely used disinfectant for pools, renowned for its effectiveness.

Chlorine Consumption:

This refers to the rate at which chlorine is used up by contaminants like bacteria, algae, and organic debris. Chlorine must first satisfy this demand before it can effectively sanitize the pool.

Active Chlorine:

This is the amount of chlorine available for disinfection after the chlorine demand has been met.

Weak Chlorine:

This is chlorine that has already reacted with contaminants and is less effective as a disinfectant.

Cyanuric Acid:

Also known as a stabilizer or conditioner, this chemical prolongs the effectiveness of chlorine by reducing its breakdown due to sunlight.

DPD1 & DPD3:

These are indicator solutions used to measure active and total chlorine levels, respectively.

Dry Acid:

Also known as sodium bisulfate, this granular substance is used to lower pH and total alkalinity.

Effective Chlorine:

This is the chlorine in its active form, responsible for killing bacteria and algae.

Water Hardness:

This measures the levels of calcium or magnesium in the water, which can lead to scale formation if too high.

Hypochlorous Acid:

This is the active form of chlorine that performs the sanitizing and oxidizing actions.

Muriatic Acid:

This liquid acid is used to decrease pH and total alkalinity levels.


An outdated indicator solution formerly used to measure total chlorine levels.


This scale measures the water's acidity or alkalinity. A reading above 7 is alkaline, while below 7 is acidic.


Stands for 'parts per million,' the standard unit for measuring chemical concentrations in pools.

Phenol Red:

An indicator solution used for measuring pH levels.


Also known as super-chlorination, this involves adding a large dose of chlorine to eliminate algae and other contaminants.

Soda Ash:

Also known as sodium carbonate, this substance raises the water's pH levels.

Sodium Bicarbonate:

This is used to increase the water's total alkalinity and pH levels.


Also known as cyanuric acid or conditioner, this chemical extends the lifespan of chlorine in the water by reducing its breakdown due to sunlight.


This is the practice of adding a high dose of chlorine, usually 5-10 times the daily amount, to deal with algae blooms or after heavy usage or rainfall.

Total Alkalinity:

This helps the water maintain stable pH levels.

Total Chlorine:

This is the sum of active and weak chlorine in the water.

We hope this glossary helps you better understand the chemicals and terms involved in pool maintenance. With this knowledge, you'll be well-equipped to keep your pool in top condition.

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