---
title: "Pool Water Chemistry 101: pH, Chlorine, Alkalinity & More | Pool Pros"
url: https://poolpros.ai/learn/pool-maintenance/water-chemistry-basics
description: "Understand pool water chemistry fundamentals. Learn ideal ranges for pH, chlorine, alkalinity, calcium hardness, and stabilizer."
lang: en
---

Pool Maintenance Hub (https://poolpros.ai/learn/pool-maintenance)

# Pool Water Chemistry 101

Balanced water chemistry is the foundation of a safe, clear, and equipment-friendly pool. Understanding the key parameters helps you communicate with your pool company and catch problems early.

## pH (7.2-7.6)

pH measures acidity/alkalinity. Low pH (<7.2) causes eye irritation, plaster etching, and metal corrosion. High pH (>7.8) reduces chlorine effectiveness and causes scale buildup. Muriatic acid lowers pH; soda ash raises it.

## Free Chlorine (1-4 ppm)

Chlorine is your primary sanitizer. Below 1 ppm, bacteria and algae can grow. Above 5 ppm, swimming becomes uncomfortable. Maintain 2-4 ppm for optimal sanitation and comfort. For salt pools, the salt cell produces chlorine automatically.

## Total Alkalinity (80-120 ppm)

Alkalinity buffers pH, preventing rapid swings. Low alkalinity causes pH bounce. High alkalinity makes pH difficult to adjust. Sodium bicarbonate raises TA; muriatic acid lowers it.

## Calcium Hardness (200-400 ppm)

Too-low calcium causes the water to become aggressive and dissolve plaster and metal fittings. Too-high calcium causes scale deposits on surfaces and equipment. Calcium chloride raises hardness; dilution (draining and refilling) lowers it.

Pro Tip

In hard-water areas, monitor calcium closely - scale buildup is one of the most common and expensive problems to fix.

## Cyanuric Acid / Stabilizer (30-50 ppm)

Stabilizer protects chlorine from UV degradation. Without it, sunlight destroys chlorine within hours. Too-high levels (>80 ppm) reduce chlorine effectiveness, requiring partial drain. This is the most misunderstood pool chemical.

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