Pool Chemistry 101: Understanding Your Pool Water Balance

Perfect pool water isn't magic—it's chemistry. Understanding the basics of pool water balance helps you maintain a safe, sparkling pool while protecting your equipment and surfaces. This guide breaks down pool chemistry in simple terms for Central Florida pool owners.

Why Pool Chemistry Matters

The Balancing Act

Pool water chemistry affects:

• Water clarity (cloudy vs. crystal clear)
• Swimmer comfort (burning eyes, skin irritation)
• Sanitation effectiveness (killing bacteria and algae)
• Equipment longevity (pumps, filters, heaters)
• Surface protection (plaster, tile, vinyl)
• Operating costs (chemical usage, repairs)

The Cost of Imbalanced Water

Poor water chemistry causes:

• Algae growth and green water
• Cloudy, uninviting water
• Eye and skin irritation
• Equipment corrosion and scale
• Surface damage and staining
• Increased chemical costs
• Expensive repairs

Prevention through proper chemistry is always cheaper than correction.

The Essential Chemical Parameters

1. pH: The Foundation

What It Is: pH measures water acidity or alkalinity on a 0-14 scale:

• 0-6.9: Acidic
• 7.0: Neutral
• 7.1-14: Alkaline (basic)

Ideal Range: 7.2-7.6

Why It Matters:

• Affects chlorine effectiveness
• Impacts swimmer comfort
• Influences equipment corrosion
• Affects surface integrity

Too Low pH (Acidic - Below 7.0):

• Corrosive to equipment
• Damages plaster and grout
• Causes eye and skin irritation
• Rapidly depletes chlorine
• Etches surfaces

Too High pH (Alkaline - Above 7.8):

• Reduces chlorine effectiveness
• Causes cloudy water
• Scales equipment and surfaces
• Irritates eyes and skin
• Wastes chemicals

How to Adjust:

• Raise pH: Add soda ash (sodium carbonate)
• Lower pH: Add muriatic acid or dry acid

Central Florida Note: Our hard water tends to drive pH up, requiring regular acid additions.

2. Total Alkalinity: The pH Buffer

What It Is: Measure of water's ability to resist pH changes. Acts as a "pH buffer."

Ideal Range: 80-120 ppm

• Plaster pools: 80-100 ppm
• Vinyl/fiberglass: 100-120 ppm

Why It Matters:

• Stabilizes pH
• Prevents pH bounce
• Protects surfaces
• Improves water balance

Too Low Alkalinity (Below 80 ppm):

• pH fluctuates wildly
• Corrosion increases
• Staining occurs
• Surface etching

Too High Alkalinity (Above 150 ppm):

• pH difficult to lower
• Cloudy water
• Scaling occurs
• Reduced chlorine effectiveness

How to Adjust:

• Raise alkalinity: Add sodium bicarbonate (baking soda)
• Lower alkalinity: Add muriatic acid gradually

Adjustment Strategy: Always adjust alkalinity before pH. Alkalinity changes affect pH, but not vice versa.

3. Chlorine: The Sanitizer

What It Is: Primary sanitizer that kills bacteria, viruses, and algae.

Ideal Range: 1-3 ppm

• Minimum: 1 ppm
• Ideal: 2-3 ppm
• Maximum: 5 ppm (for shock treatment)

Types of Chlorine:

Free Chlorine:

• Active, available chlorine
• Does the sanitizing work
• What you want to measure

Combined Chlorine (Chloramines):

• Used-up, ineffective chlorine
• Causes "chlorine smell"
• Irritates eyes and skin
• Indicates need to shock

Total Chlorine:

• Free + Combined chlorine
• Less important than free chlorine

Chlorine Forms:

• Liquid chlorine: Sodium hypochlorite, 10-12% strength
• Granular chlorine: Di-chlor or cal-hypo
• Tablets: Tri-chlor, slow-dissolving
• Salt chlorinator: Generates chlorine from salt

Too Low Chlorine (Below 1 ppm):

• Algae growth
• Bacteria multiplication
• Green or cloudy water
• Unsafe swimming conditions

Too High Chlorine (Above 5 ppm):

• Eye and skin irritation
• Chemical smell
• Bleaching of swimwear
• Chemical waste

How to Adjust:

• Raise chlorine: Add chlorine product
• Lower chlorine: Stop adding, let sunlight dissipate, or add neutralizer

Central Florida Challenge: Intense UV radiation depletes chlorine rapidly. May need stabilizer (cyanuric acid) to protect chlorine.

4. Cyanuric Acid (Stabilizer): Chlorine's Sunscreen

What It Is: Protects chlorine from UV degradation.

Ideal Range: 30-50 ppm

• Minimum: 30 ppm (for outdoor pools)
• Maximum: 50 ppm (higher reduces effectiveness)

Why It Matters:

• Prevents rapid chlorine loss
• Reduces chemical costs
• Maintains consistent sanitization

Too Low Stabilizer (Below 30 ppm):

• Rapid chlorine depletion
• High chemical costs
• Inconsistent sanitization
• Chlorine loss from sunlight

Too High Stabilizer (Above 80 ppm):

• Reduces chlorine effectiveness
• Requires higher chlorine levels
• "Chlorine lock" conditions
• Difficult to correct (requires partial drain)

How to Adjust:

• Raise: Add cyanuric acid (stabilizer)
• Lower: Partially drain and refill (only option)

Important Notes:

• Trichlor tablets contain stabilizer
• Salt pools need manual stabilizer addition
• Stabilizer doesn't dissipate—only accumulates
• Test seasonally

Central Florida Recommendation: With year-round sun exposure, maintain 40-50 ppm for best protection.

5. Calcium Hardness: The Surface Protector

What It Is: Measure of dissolved calcium in water.

Ideal Range: 200-400 ppm

• Plaster pools: 200-275 ppm
• Vinyl/fiberglass: 175-225 ppm
• Tile pools: 200-400 ppm

Why It Matters:

• Protects plaster surfaces
• Prevents equipment corrosion
• Reduces scaling
• Maintains water balance

Too Low Calcium (Below 150 ppm):

• Corrosive water
• Etches plaster
• Damages grout
• Pits concrete

Too High Calcium (Above 500 ppm):

• Scale formation
• Cloudy water
• Equipment damage
• Filter problems

How to Adjust:

• Raise: Add calcium chloride
• Lower: Partially drain and refill, use sequestering agent

Central Florida Challenge: Municipal water is very hard (high calcium). Frequent top-offs increase calcium. Regular testing essential.

6. Total Dissolved Solids (TDS)

What It Is: Total of all dissolved substances in water.

Ideal Range: Below 1,500 ppm above fill water

Why It Matters:

• Affects water clarity
• Reduces chemical effectiveness
• Impacts equipment performance

Too High TDS (Above 3,000 ppm):

• Cloudy water
• Reduced chemical effectiveness
• Increased scaling
• Difficult to balance

How to Adjust:

• Only solution: Partial drain and refill

When to Test:

• Annually
• When water won't balance
• If water looks "old"

The LSI: Langelier Saturation Index

Understanding Water Balance

What It Is: Mathematical formula combining pH, alkalinity, calcium hardness, and temperature to determine water balance.

LSI Scale:

• Negative (-0.3 to -0.5): Corrosive
• Zero (±0.3): Balanced (ideal)
• Positive (+0.3 to +0.5): Scaling

Why It Matters: True water balance considers all factors together, not just individual parameters.

How to Calculate: Use online LSI calculator or pool chemistry app. Input:

• pH
• Total alkalinity
• Calcium hardness
• Water temperature
• TDS

Goal: Maintain LSI between -0.3 and +0.3

Central Florida Tip: Higher summer temperatures affect LSI. Adjust chemistry seasonally.

Testing Your Pool Water

Testing Frequency

Home Testing:

• pH and chlorine: 2-3 times weekly
• Alkalinity: Weekly
• Calcium: Monthly
• Stabilizer: Seasonally
• TDS: Annually

Professional Testing:

• Complete analysis: Every 2-3 months
• Problem diagnosis: As needed
• Season start: Spring
• Season end: Fall

Testing Methods

Test Strips:

• Pros: Quick, easy, inexpensive
• Cons: Less accurate, limited parameters
• Best for: Daily monitoring

Liquid Test Kits (Drop Tests):

• Pros: More accurate, reliable
• Cons: Slower, more complex
• Best for: Weekly comprehensive testing

Digital Testers:

• Pros: Highly accurate, easy to read
• Cons: Expensive, require calibration
• Best for: Serious pool owners

Professional Lab Testing:

• Pros: Most accurate, comprehensive
• Cons: Cost, turnaround time
• Best for: Quarterly analysis, problem-solving

Testing Tips for Accuracy

1. Sample from elbow-depth water

   • Not near returns or skimmers
   • Away from recently added chemicals

2. Test immediately

   • Results change as sample sits

3. Follow instructions exactly

   • Correct drop counts
   • Proper reaction times
   • Accurate comparisons

4. Replace test kits annually

   • Reagents expire
   • Results become inaccurate

5. Test before adding chemicals

   • Know starting point
   • Determine needed adjustments

Balancing Your Pool Chemistry

The Correct Order

Follow This Sequence:

1. Test all parameters
2. Adjust total alkalinity (if needed)
3. Adjust pH (if needed)
4. Adjust calcium hardness (if needed)
5. Adjust chlorine (always last)
6. Retest after 4-8 hours

Why Order Matters:

• Alkalinity affects pH
• pH affects chlorine effectiveness
• Changes interact with each other

Chemical Addition Guidelines

Safe Chemical Handling:

• Wear safety gear (glasses, gloves)
• Add chemicals separately (never mix)
• Add to water, not water to chemicals
• Store safely away from children/pets
• Follow product instructions exactly

Dissolution Methods:

• Liquids: Pour slowly around pool perimeter
• Granules: Dissolve in bucket first, then add
• Tablets: Use floater or automatic feeder

Wait Times:

• Between different chemicals: 4+ hours
• Before swimming: Check product label
• Before retesting: 4-8 hours

Common Chemical Adjustments

Raise pH:

• Use soda ash (sodium carbonate)
• Amount: 6 oz per 10,000 gallons raises pH by 0.2

Lower pH:

• Use muriatic acid or dry acid
• Amount: 1 quart acid per 10,000 gallons lowers pH by 0.2

Raise Alkalinity:

• Use sodium bicarbonate (baking soda)
• Amount: 1.5 lbs per 10,000 gallons raises alkalinity by 10 ppm

Raise Chlorine:

• Liquid chlorine, granular, or tablets
• Amount: 1 gallon liquid raises chlorine by 1-2 ppm per 10,000 gallons

Raise Calcium:

• Use calcium chloride
• Amount: 2 lbs per 10,000 gallons raises calcium by 20 ppm

Add Stabilizer:

• Use cyanuric acid
• Amount: 1 lb per 10,000 gallons raises stabilizer by 10 ppm

Shocking Your Pool

What Is Shocking?

Definition: Raising chlorine to 10+ ppm to:

• Oxidize contaminants
• Kill chloramines
• Eliminate algae
• Restore water clarity

When to Shock:

• Weekly during heavy use
• After heavy rain
• After pool party
• When water smells like chlorine
• When combined chlorine is above 0.5 ppm
• If water is cloudy
• To kill algae

Types of Shock:

• Calcium hypochlorite (cal-hypo): Most common, strong, contains calcium
• Sodium di-chlor: Dissolves quickly, won't cloud water
• Liquid chlorine: Convenient, no residue
• Non-chlorine shock: Oxidizer only, can swim immediately

How to Shock Properly

Steps:

1. Test water chemistry
2. Balance pH to 7.2-7.4
3. Calculate pool volume
4. Determine shock amount needed
5. Dissolve shock in bucket (if using granular)
6. Add slowly around pool perimeter
7. Run pump 8-12 hours
8. Retest before swimming

Amount:

• Standard shock: 1 lb per 10,000 gallons
• Heavy shock: 2-3 lbs per 10,000 gallons
• Green pool: 3-5+ lbs per 10,000 gallons

Timing:

• Shock at dusk or night (UV degrades chlorine)
• Run pump overnight
• Test before morning swimming

Troubleshooting Common Chemistry Problems

Cloudy Water

Possible Causes:

• Poor filtration
• Low chlorine
• High pH
• High alkalinity
• High calcium
• Poor circulation
• Algae beginning

Solutions:

1. Test all parameters
2. Adjust pH to 7.2-7.4
3. Shock pool
4. Clean/backwash filter
5. Run pump 24 hours
6. Add clarifier if needed

Green Water (Algae)

Causes:

• Low chlorine
• Poor circulation
• High phosphates
• Lack of brushing

Solutions:

1. Brush entire pool thoroughly
2. Test and balance pH
3. Super-shock (3x normal)
4. Run filter continuously
5. Brush again after 24 hours
6. Vacuum to waste
7. Clean filter
8. Retest and adjust

Burning Eyes

Causes:

• High combined chlorine (not high free chlorine!)
• Imbalanced pH
• High chloramines

Solutions:

1. Test free vs. total chlorine
2. Shock pool to break chloramines
3. Balance pH to 7.2-7.6
4. Improve circulation

Strong Chlorine Smell

Cause: Combined chlorine (chloramines), NOT too much chlorine

Solution: Shock pool to break chloramines

Scale on Surfaces

Causes:

• High pH
• High alkalinity
• High calcium hardness
• High water temperature

Solutions:

1. Lower pH to 7.0-7.2
2. Reduce alkalinity if high
3. Brush scale
4. Use sequestering agent
5. Consider partial drain if calcium very high

Central Florida-Specific Chemistry Challenges

Hard Water

Issue: High calcium in municipal water

Management:

• Test calcium regularly
• Consider softener for fill water
• Use sequestering agents
• Plan for periodic partial drain

High pH Drift

Issue: Water pH constantly rises

Management:

• Regular acid additions
• Maintain proper alkalinity
• Test more frequently
• Consider automated pH control

Rapid Chlorine Loss

Issue: Intense UV depletes chlorine

Management:

• Maintain stabilizer 40-50 ppm
• Use covered tablet feeder
• Consider salt system
• Increase circulation during peak sun

Phosphates from Fertilizer

Issue: Lawn fertilizer washing into pool

Management:

• Regular phosphate testing
• Phosphate remover treatments
• Improve pool drainage
• Schedule treatments after heavy rain

Afternoon Storms

Issue: Rain dilutes chemicals and adds contaminants

Management:

• Test after storms
• Shock if needed
• Maintain higher baseline chlorine
• Good drainage around pool

Automated Chemistry Solutions

Salt Chlorine Generators

Benefits:

• Consistent chlorination
• Softer water feel
• Lower maintenance
• Reduced chemical handling

Requirements:

• Manual stabilizer addition
• Regular cell cleaning
• Salt additions as needed
• pH monitoring (tends to rise)

Chemical Controllers

Types:

• pH controllers
• ORP (chlorine) controllers
• Complete automation systems

Benefits:

• Automated chemistry adjustment
• Consistent water quality
• Reduced testing frequency
• Chemical savings

Considerations:

• Higher initial cost
• Requires calibration
• Probe maintenance
• Still need periodic testing

Professional Help

When to Call a Professional

Situations:

• Unable to balance chemistry
• Recurring problems
• Water won't clear
• Equipment concerns
• Major chemical adjustments needed
• Lack of time or confidence

Professional Services:

• Comprehensive water analysis
• Expert problem diagnosis
• Proper chemical dosing
• Equipment inspection
• Education and guidance

Conclusion

Understanding pool chemistry isn't complicated once you learn the basics. Consistent testing, prompt adjustments, and proactive maintenance keep your Central Florida pool perfect year-round.

Need help with pool chemistry? Contact Central Florida Pool & Spa at (863) 353-6873. Our experienced technicians provide expert water analysis, chemical balancing, and education throughout Osceola, Orange, and Polk Counties. We make pool chemistry simple so you can enjoy swimming.