Maintaining safe and clean water in pools and spas: A simple guide

What you need to know:

Water Sanitation and Balance: Keeping recreational water clean and safe involves both sanitation (killing bacteria and algae) and maintaining water balance (ensuring optimal levels of pH, alkalinity, hardness, and total dissolved solids).
Sanitizers and Oxidizers: Chlorine and bromine are common sanitizers. Chlorine acts as both sanitizer and oxidizer, while bromine requires a separate oxidizer to effectively break down waste products.
Chlorine Chemistry: Understanding the different forms of chlorine, including free available chlorine (FAC), combined chlorine (chloramines), and total chlorine, is essential for effective sanitation. Breakpoint chlorination is a key concept for eliminating chloramines and achieving optimal sanitation.
Alternative Sanitizers: Alternatives to chlorine and bromine include chlorine generators, ozone, ultraviolet light, and ionization of salts. Each method has its own advantages and limitations.
Other Pool Chemicals: Additional chemicals are often required to address specific conditions, such as flocculants for water clarity, degreasers for filter maintenance, defoamers, and cyanuric acid (stabilizer) to protect chlorine from sunlight degradation.
Water Balance Parameters: Maintaining balanced water involves understanding and adjusting pH, total alkalinity, calcium hardness, and total dissolved solids.
Testing and Adjustments: Regular water testing is crucial for monitoring chemical levels and making necessary adjustments. Various test kits, including DPD and OTO for chlorine, phenol red for pH, and titration tests for alkalinity and hardness, are used.
Troubleshooting: The guide provides solutions for common water problems such as cloudy water, discolouration, corrosion, scaling, and algae growth.

Important Ideas and Facts:

Sanitizers:

Chlorine:“Chlorine has been somewhat of a wonder drug for pool and spa environments. It has the power to kill bacteria and algae — and works extremely well in aqueous environments.”
Chlorine can exist as free available chlorine (FAC), the active sanitizing form, combined chlorine (chloramines), which is less effective and causes irritation, and total chlorine, which is the sum of FAC and combined chlorine.
Breakpoint chlorination involves adding sufficient chlorine to oxidize all chloramines, resulting in a sudden drop in chlorine residual and improved water quality.
Bromine:“Bromine also has no odor, and dispensing it your spa via a feeder allows it to dissolve at a slow, constant, desirable rate. Just be sure to remove the feeder when your spa is in use.”
Bromine is effective as a sanitizer but does not oxidize well, requiring a separate oxidizer.
It is more suitable for indoor pools and spas as sunlight can significantly deplete its residual.

Water Balance:

pH:“The most fragile and arguably the most important component of water balance is pH, a reading that indicates how acidic or basic your pool and spa water is.”
Ideal pH range: 7.4-7.6 for pools, 7.2-7.8 for spas.
pH affects sanitizer effectiveness, pool surfaces, equipment, and swimmer comfort.
Total Alkalinity:“The most important thing to remember about total alkalinity is that it affects your pH levels and therefore must be tested before you do any pH testing and adjustments.”
Ideal range: 80-140 ppm for pools, 80-120 ppm for spas.
Alkalinity acts as a buffer, preventing drastic pH fluctuations.
Calcium Hardness:“Note: You do want your water to have some level of hardness. If it’s too soft, the water will slowly but surely dissolve the plaster and any metal in your pool and spa equipment.”
Ideal range: 200-400 ppm for both pools and spas.
Proper hardness prevents etching and corrosion of surfaces and equipment.
Total Dissolved Solids (TDS):“High TDS – at 1,500 ppm above water-supply level – can reduce chlorine efficiency by as much as 50%.”
Ideal range: 1,000-2,000 ppm for pools, 1,500 ppm above start-up TDS for spas.
High TDS can affect chlorine efficiency, water clarity, and taste.

Testing:

DPD Test: Preferred method for measuring free available chlorine, providing a more accurate assessment of sanitizing power.
OTO Test: Measures total chlorine but does not differentiate between free and combined chlorine.
Phenol Red Test: Common method for measuring pH levels.
Titration Tests: Used for determining total alkalinity and calcium hardness.

Cyanuric Acid (Stabilizer):

“Chlorine in outdoor pools must be shielded from the degrading effects of the sun’s ultraviolet (UV) rays. Cyanuric acid is used in outdoor pools…”
Recommended level: 30-50 ppm, with a maximum of 100 ppm.
Cyanuric acid protects chlorine from degradation by sunlight, improving its effectiveness and longevity.

Key Takeaways:

Maintaining safe and clean recreational water requires regular monitoring and adjustment of chemical levels.
Understanding the interactions between different water balance parameters is crucial for effective treatment.
Proper testing procedures are essential for obtaining accurate readings and making informed adjustments.
Consult with pool/spa professionals when encountering persistent problems or uncertainties.