Water Chemistry

A strong chlorine smell with a low test reading almost always means chloramines, not too much chlorine. Chlorine reacts with sweat, oils, urine and other nitrogen compounds and gets used up forming smelly byproducts, leaving little active chlorine behind to test for. The smell signals used-up chlorine, not fresh chlorine. Why does the pool smell … Read more

“Chlorine lock” is a nickname, not an official chemical term — it describes chlorine that stops sanitizing effectively, usually because cyanuric acid (stabilizer) has built up too high, or because something in the water is consuming chlorine faster than it can work. Testing, not guessing, tells you which. What does “chlorine lock” actually mean? Pool … Read more

Cyanuric acid is a chemical compound that shields chlorine from being broken down by sunlight. It’s nicknamed “pool stabiliser” because it stabilises chlorine’s strength outdoors — without it, UV rays can burn off unprotected chlorine surprisingly fast, especially in strong sun. Many chlorine products already contain it. What does cyanuric acid actually do in a … Read more

Calcium hardness matters because it controls whether pool water pulls calcium out of plaster, grout and equipment (when it’s too low) or deposits scale onto surfaces and clogs plumbing (when it’s too high). Keeping it in a reasonable range protects the pool’s finish and its circulation system over time. What is calcium hardness, exactly? Calcium … Read more

Total alkalinity measures how much dissolved mineral buffer is in the water — mainly bicarbonates — while pH measures how acidic or basic the water actually is right now. Alkalinity is the water’s resistance to pH change; pH is the reading that resistance is protecting. They move together, but they answer different questions. What does … Read more

pH is a measure of how acidic or basic pool water is, on a scale most pools are tested against between roughly 7.2 and 7.8. It matters because pH controls how well chlorine works, how comfortable the water feels, and how much it corrodes or scales pool surfaces and equipment. What does pH actually measure? … Read more

Free chlorine is the sanitizer that is still available to kill germs and control algae. Combined chlorine is chlorine that has already reacted with contaminants and lost most of its sanitizing power. Total chlorine is simply free plus combined added together — it tells you what’s there, not how much is still working. Understanding the … Read more

Chlorine’s job in a pool is to kill bacteria, viruses and algae, and to break down organic waste like sweat, urine and sunscreen before it builds up. It does this through a chemical reaction, not by “cleaning” water the way a filter does — chlorine and filtration are two separate, equally necessary jobs. What is … Read more

Clear pool water comes from three things working together: filtration that physically removes particles, circulation that moves every gallon past that filter regularly, and balanced chemistry that keeps contaminants dissolved or destroyed instead of clouding the water. Skip any one of the three and the water dulls, no matter how much chlorine gets added. Why … Read more

Why Does Pool Water Go Cloudy? Pool water goes cloudy when tiny particles — dust, body oils, algae cells, or mineral residue — stay suspended in the water instead of settling out or being filtered away. That usually points to one of four things: weak filtration, poor circulation, unbalanced chemistry, or an early algae bloom. … Read more