🧪 Swimming Pool Chemistry Crash Course
Introduction
Keeping your pool crystal-clear isn’t just about aesthetics — it’s about health, comfort, and protecting your equipment. Water chemistry may sound technical, but once you know the basics, maintaining balanced water becomes second nature.
Poorly balanced water can lead to itchy skin, cloudy water, algae growth, and even damage to your pool equipment. But with regular testing and a few minutes of care each week, you can enjoy a sparkling pool all year round.
💡 Need professional help? Book a pool service in Sydney with Sydney Pool Servicing and we’ll take care of it for you.
🌊 Why Pool Water Chemistry Matters
Some pool owners claim they “just throw in chlorine once a week” — but that’s like filling your car with fuel and never changing the oil. It might work for a while, but the problems will come eventually.
Balancing your pool water ensures:
✅ Safe swimming — kills bacteria and harmful organisms
💧 Comfortable water — prevents red eyes and dry skin
🛠️ Protected equipment — avoids corrosion and scaling
💸 Lower costs — extends the life of heaters, filters, and pumps
A balanced pool not only looks better — it feels better and lasts longer.
🧠The Four Core Water Tests
If you only remember four things about pool chemistry, make it these:
Chlorine 2–4 ppm Sanitises and prevents algae
pH 7.4–7.6 Keeps water comfortable and non-corrosive
Total Alkalinity 80–120 ppm Stabilises pH and prevents fluctuations
Calcium Hardness 200–400 ppm Protects plaster, tiles, and metal fittings
Keep these in range and you’ll solve over 90% of water issues before they start.
⚗️ The Correct Order for Adjusting Chemicals
Balancing pool water is all about doing things in the right order:
Alkalinity – sets the foundation
pH – fine-tunes comfort and prevents corrosion
Calcium Hardness – protects the pool structure
Chlorine – sanitises when everything else is stable
If you fix things out of order, you’ll constantly be re-balancing. Small changes and patience pay off — wait at least 12–24 hours between adjustments and always retest before adding more chemicals.
đź’§ Understanding pH & Alkalinity
pH measures how acidic or basic the water is. A perfect pool sits around 7.5, matching the natural pH of your eyes and skin.
Total Alkalinity acts like a “shock absorber” — preventing the pH from swinging too high or too low when chemicals are added.
Without proper alkalinity, pH levels fluctuate wildly. Always adjust alkalinity first, then pH.
🧴 Chlorine — Your Pool’s Main Defender
Chlorine is your pool’s number-one line of defense. It:
Kills bacteria and viruses
Oxidises contaminants
Prevents algae
Builds a protective residual
Alternative systems like UV or ozone help, but none replace chlorine entirely. Maintain a steady 2–4 ppm for safe, clear water.
For professional chemical balancing, see our
👉 Green Pool Recovery service.
🧢 Cyanuric Acid (Stabiliser)
Cyanuric Acid (CYA) protects chlorine from being destroyed by sunlight.
Ideal range: 30–50 ppm
Too low: Sunlight burns chlorine away too quickly
Too high (80+ ppm): Chlorine becomes less effective
If your stabiliser creeps too high, you’ll need to partially drain and refill the pool with fresh water to lower it.
🪨 Calcium Hardness & The Saturation Index
“Hard water” isn’t just for kettles — it affects pools too.
Low calcium: Corrosive water that eats away at concrete and metal
High calcium: Scale buildup on heaters and tiles
Keep hardness between 200–400 ppm. Balancing calcium also helps maintain the Langelier Saturation Index (LSI) — the measure of whether your water is corrosive, neutral, or scale-forming.
🌿 Phosphates, Metals & Other Trouble-Makers
A few extra elements can quickly throw your pool off balance:
SubstanceIdeal LevelProblem When Too HighPhosphates<500 ppbFeeds algae and depletes chlorineIron0 ppmBrown stains or cloudy waterCopper0 ppmGreen hair or surface staining
If you notice these issues, you may need a metal remover or phosphate treatment. We can test and correct these during a Regular Pool Service.
🧂 How to Add Pool Chemicals Safely
Always handle pool chemicals with care:
❌ Never mix chemicals together
⏱️ Add one chemical at a time (wait at least an hour between)
🪣 Dissolve granules first in a bucket before adding
đź’¨ Pour liquids slowly in front of a return jet
🧽 Brush after adding to prevent stains or residue
Follow product instructions carefully — every brand has slightly different dosages and safety steps.
🧪 How Often Should You Test Pool Water?
Beginners: Test daily for the first few weeks
Regular maintenance: 2–3 times per week
After rain or heavy use: Test again immediately
Monthly: Get a professional test for accuracy
Use test strips for quick checks, but invest in a DPD liquid kit for precision. Consistent testing helps you understand your pool’s “personality” and how it reacts to weather, heat, or use.
🧰 The 30-Minute Rule
You can keep your pool perfect with just 30–60 minutes per week:
Skim and remove debris
Empty baskets
Vacuum
Backwash or rinse filters
Test and adjust chemistry
With consistency, your pool stays sparkling and easy to manage — no surprises, no green water, and more time swimming.
đź’¦ Need Help Balancing Your Pool?
Sydney Pool Servicing offers professional:
âś… Regular pool cleaning & chemical testing
🌿 Green pool recovery
⚙️ Equipment installation & advice
đź’§ Water balancing & troubleshooting
đź“Ť Servicing the Inner West, Eastern Suburbs, Sutherland Shire, and Parramatta.
👉 Book your pool service now.
