Essential Pool Chemistry Adjustments Before Closing Season
When closing a pool for the season, chemical balance is not optional; it’s essential. Poor pool chemistry at closing can lead to staining, equipment corrosion, algae growth, and costly repairs come spring. Whether you’re managing a commercial aquatic facility or a residential pool in New Jersey, making the correct pool chemistry adjustments before closing ensures your pool stays protected and compliant throughout the offseason.
Why Proper Pool Chemistry Matters Before Seasonal Closure
Preventing Damage to Pool Surfaces and Equipment
Incorrect water balance over the winter can deteriorate surfaces and damage internal components. For example, low pH can lead to etching and corrosion, while high calcium levels can result in scaling. Both scenarios are costly and easily preventable with the right chemistry adjustments.
Reducing Algae Growth and Water Contamination Risks
Algae thrives in poorly sanitized or unbalanced water. Closing a pool with proper sanitizer levels and considering an algaecide treatment, reduces the risk of green water and microbial contamination when reopening.
Health and Safety Standards Compliance
Pools, especially commercial ones, must adhere to local health codes. Certified Pool Operators (CPO®) are responsible for ensuring that water chemistry meets regulatory standards even before closing. Maintaining proper chemical levels helps operators avoid violations and maintain a safe swimming environment year-round.
When to Start Preparing Pool Chemistry for Closure
In states like New Jersey, pools typically close when temperatures drop consistently below 65°F, usually around mid to late fall. Waiting too long into colder months may lead to freezing issues, while closing too early can create algae problems. It’s best to balance and adjust chemistry while water temperatures are cool but not yet frigid, allowing chemicals to circulate properly.
Key Pool Chemistry Adjustments to Make Before Closing
Proper pool chemistry adjustments involve targeting ideal ranges to ensure water balance throughout winter.
Balancing pH Levels (Ideal Range: 7.2–7.8):
Maintaining pH in this range helps prevent scaling and corrosion. A pH below 7.2 is acidic, which can damage metal components, while a pH above 7.8 may lead to cloudy water and scale buildup.
Adjusting Total Alkalinity (Ideal Range: 80–120 ppm):
Alkalinity acts as a buffer for pH stability. If total alkalinity is too low, pH can fluctuate wildly. If it’s too high, pH becomes difficult to adjust. Use sodium bicarbonate to raise alkalinity and muriatic acid to lower it, as needed.
Stabilizing Calcium Hardness (Ideal Range: 200–400 ppm):
Calcium hardness affects both surface integrity and equipment longevity. Low levels can cause water to leach minerals from pool surfaces, while high levels lead to scaling. Adjust using calcium chloride or dilute water if levels are too high.
Chlorine or Sanitizer Levels (Free Chlorine: 1.0–3.0 ppm):
Even during closure, a residual sanitizer level is essential. Most experts recommend shocking the pool before closing to ensure sanitation through the dormant months.
Shock Treatment and Algaecide Application:
Shocking the pool (superchlorination) eliminates contaminants and organic material. After shocking, apply a non-copper-based algaecide to provide residual protection without staining.
Ensuring Cyanuric Acid Levels Are in Range (30–50 ppm):
Cyanuric acid (stabilizer) protects chlorine from degradation by sunlight. If levels are too high, it can reduce chlorine effectiveness. Dilution may be necessary if stabilizer levels exceed 100 ppm.
Equipment and Water Testing Tips for Accuracy
Using DPD Test Kits for Chlorine Accuracy:
The DPD test method is recommended for accurate free and total chlorine readings. It’s the preferred standard in pool operation due to its reliability and compliance with local health codes.
Recording and Reporting for Certified Pool Operators:
CPO®s are responsible for logging chemical levels and adjustments. Maintaining a detailed record before winterization supports future inspections and demonstrates regulatory compliance.
Common Mistakes to Avoid During End-of-Season Pool Chemistry Adjustments
Overdosing Chemicals: Adding excessive chemicals can throw off water balance, damage liners, and cause scale. Always refer to manufacturer dosing guidelines and verify with accurate test readings.
Closing Without Final Shock Treatment: Skipping shock treatment allows microorganisms to survive the winter, creating issues at reopening. Shocking should be done 24–48 hours before closing, allowing circulation and proper sanitization.
Ignoring Calcium and Cyanuric Acid Balancing: These two factors are often overlooked. Imbalanced calcium can destroy pool surfaces over time, and elevated cyanuric acid can impair chlorine efficiency, even in cooler months.
Schedule a Certified Inspection Before You Close
As a nationally recognized leader in pool safety and compliance, Pool Operation Management provides certified inspections, water testing, and closing services tailored to your pool’s unique needs. Whether you manage a hotel pool or a backyard oasis, our team ensures safe, code-compliant shutdowns. Contact us today to schedule your pre-closing inspection!
