🧪 Quick Reference
Total alkalinity (TA) is one of the most important yet misunderstood aspects of pool water chemistry. It measures your water's ability to resist changes in pH, acting as a buffer that keeps your pH stable even when acids or bases are added to the pool.
Understanding TA | Testing & Ranges | Adjustment | TA-pH Relationship | Water Balance | Common Problems | Pro Tips
Understanding Total Alkalinity
Think of total alkalinity as your pool's shock absorber for pH changes. When TA is properly balanced, your pH remains stable despite influences like swimmer load, rainfall, chemical additions, or environmental factors. When TA is too low, your pH will swing wildly up and down. When it's too high, your pH becomes difficult to adjust and tends to drift upward.
Total alkalinity is measured in parts per million (ppm) and represents the concentration of alkaline substances in your water, primarily bicarbonates, carbonates, and hydroxides.
Ideal Range and Testing
The optimal total alkalinity range is 80-120 ppm for most pools, with 100 ppm being ideal. Some variations exist based on pool type and sanitizer:
- Salt Systems or Liquid Chlorine: Often run better at lower Alkalinity (60–80 ppm) to prevent pH from rising too fast
- Trichlor Tablet users: Need to watch out—tablets are acidic and will lower your Alkalinity over time, requiring regular top-ups with baking soda
| TA Level | Status | Effect |
|---|---|---|
| Under 70 ppm | ❌ Too Low | pH bounces erratically, equipment corrosion risk |
| 80-120 ppm | ✅ Ideal | Perfect pH stability, balanced water chemistry |
| 150+ ppm | ❌ Too High | pH drifts high, scaling, cloudy water, poor chlorine efficiency |
Test total alkalinity weekly using a reliable test kit. Digital testers and quality drop-based test kits provide the most accurate readings. Test strips can work for quick checks but aren't as precise for TA measurements.
📝 Note for High Stabilizer (CYA) Levels
If CYA is elevated, measured TA includes cyanurate alkalinity. For water-balance (LSI) decisions, use carbonate alkalinity ≈ TA − (CYA/3). Don't raise TA just because CYA is high—target stable pH control and balanced LSI. For example, with 90 ppm CYA, your "true" carbonate alkalinity (the part that actually buffers pH) is about 30 ppm less than your test reading.
• Total Alkalinity Test Kits: Dedicated TA measurement for accurate readings
• Multi-Parameter Test Kits: Complete water analysis including TA
• Digital Water Testers: Professional-grade precision testing
Adjusting Total Alkalinity
Raising TA
Add sodium bicarbonate (baking soda) when TA is below 80 ppm. Use about 1.5 pounds per 10,000 gallons to raise TA by 10 ppm. Add in portions, allow circulation, then retest.
• 10,000 gallons: 1.5 lbs sodium bicarbonate = +10 ppm TA
• 20,000 gallons: 3 lbs sodium bicarbonate = +10 ppm TA
Dissolve in bucket of water before adding to pool
Lowering TA
Add muriatic acid or sodium bisulfate when TA is above 150 ppm. This is trickier because lowering TA also lowers pH. Use an acid demand test (add small amounts of acid while monitoring pH drop) or online calculators to determine the right amount. You'll need to aerate the water (fountains, waterfalls, or air blower) to raise pH back up while keeping TA down.
1. Add acid to lower both TA and pH
2. Aerate water heavily (fountains, jets, air blower)
3. pH rises while TA stays down
4. Repeat until TA reaches target range
⚠️ This process takes time—plan for several days of adjustment cycles
• Sodium Bicarbonate (Baking Soda): Food-grade or pool-specific TA increaser
• Muriatic Acid: Liquid acid for lowering TA—use with caution
• Sodium Bisulfate (Dry Acid): Safer granular alternative to muriatic acid
The TA-pH Relationship
Total alkalinity and pH are closely linked but serve different purposes:
- TA provides pH stability (buffering capacity)
- pH affects swimmer comfort and chemical effectiveness
- Adjust TA first, then fine-tune pH
- High TA makes pH hard to lower and causes pH drift
Water Balance Connection
Total alkalinity is a key component of overall water balance, working alongside pH, calcium hardness, and temperature in the Langelier Saturation Index (LSI). Proper TA levels help prevent both corrosive conditions (which damage equipment and surfaces) and scaling conditions (which cause cloudy water and surface deposits).
Common Problems
Low TA (below 70 ppm)
- pH bounces erratically
- Equipment corrosion
- Plaster etching
- Swimmer discomfort
- Difficulty maintaining stable water chemistry
High TA (above 150 ppm)
- pH constantly drifts high
- Cloudy water
- Scaling on surfaces and equipment
- Reduced chlorine effectiveness
- Difficulty lowering pH
"My pH keeps bouncing around!"
Most likely cause: Total alkalinity is too low (under 70 ppm).
Solution: Raise TA to 80-120 ppm using sodium bicarbonate, then adjust pH.
"I can't get my pH down no matter how much acid I add!"
Most likely cause: Total alkalinity is too high (over 150 ppm).
Solution: Lower TA using the acid/aerate process described above.
Pro Tips
🎯 Expert TA Management Tips
- Always adjust TA before adjusting pH—it's the foundation of water balance
- Aerate water when lowering TA to prevent pH from dropping too low
- Use the saturation index (LSI) to balance TA with other water chemistry factors
- Trichlor tablet users: Check TA weekly and add baking soda regularly to counteract acid consumption
- Make gradual adjustments over several days rather than large corrections
- Warmer water can affect the TA-pH relationship, so test more frequently in summer
- Keep detailed logs of TA levels to identify patterns and prevent problems
- Don't panic if TA drifts slightly outside the ideal range—minor variations are normal
🌡️ Seasonal Considerations
TA tends to be more stable than pH, but seasonal factors can affect it. Heavy rains can lower TA, while evaporation concentrates it. Test more frequently during extreme weather or heavy pool use periods.