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Pool Alkalinity Calculator

Calculate how much baking soda to raise or muriatic acid to lower your pool's total alkalinity. Works for swimming pools, above ground pools, hot tubs, and spas.

💡

Ideal Alkalinity: 80-120 ppm for pools, 100-150 ppm for hot tubs

Always adjust alkalinity first, then pH. Alkalinity stabilizes pH and prevents wild swings.

🔺 Raise Alkalinity

Low
Ideal

💡 Tip: Add baking soda gradually. Wait 4-6 hours and retest before adding more.

📊 Baking Soda Needed

Add Baking Soda (Sodium Bicarbonate)

6 lbs

(96 oz)

Metric Equivalent

2.72 kg (2722 g)

Alkalinity Increase+40 ppm
From → To60 → 100 ppm
Pool Volume10,000 gallons

📋 How to Add:

  1. Turn on pool pump for circulation
  2. Broadcast baking soda across pool surface
  3. Wait 4-6 hours before retesting
  4. Repeat if needed (don't add all at once)

🏊 Understanding Pool Total Alkalinity

Total Alkalinity (TA) is one of the most important measurements for pool water chemistry. It acts as a buffer that prevents rapid pH fluctuations, which can damage your pool and make the water uncomfortable for swimmers.

Why Alkalinity Matters

Think of alkalinity as your pool's "shock absorber" for pH. Without proper alkalinity levels, your pH can swing wildly from high to low with even small changes—like adding a little chlorine, having swimmers in the pool, or getting some rain. This is called "pH bounce" and it causes major problems.

How to Test Alkalinity

Testing Options:

  • Test strips - Quick and easy, good for regular checks
  • Liquid test kit - More accurate, uses titration
  • Digital tester - Most accurate, higher cost
  • Pool store test - Free at most pool supply stores

Adjusting Alkalinity Step-by-Step

To raise alkalinity:

  1. Calculate the amount of baking soda needed using our calculator
  2. Turn on your pool pump for circulation
  3. Broadcast the baking soda evenly across the pool surface
  4. Wait 4-6 hours before retesting
  5. Repeat if needed (don't add all at once for large adjustments)

To lower alkalinity:

  1. Calculate the muriatic acid needed using our calculator
  2. Put on safety gear (goggles, gloves, mask)
  3. Turn OFF the pump
  4. Dilute acid in a bucket of water (10:1 ratio - water first!)
  5. Pour slowly into the deep end of the pool
  6. Wait 30 minutes, then turn pump on and circulate 6+ hours
  7. Retest before adding more

📋 Quick Reference

• Ideal TA: 80-120 ppm

• Hot tub TA: 100-150 ppm

• Test weekly minimum

• Adjust TA before pH

• Wait 4-6 hrs between doses

🧪 Chemicals Used

To Raise:

• Sodium Bicarbonate (Baking Soda)

To Lower:

• Muriatic Acid (HCl)

• Sodium Bisulfate (Dry Acid)

Frequently Asked Questions

The ideal total alkalinity (TA) for a swimming pool is 80-120 ppm (parts per million). For hot tubs and spas, aim for 100-150 ppm. Alkalinity outside this range can cause pH instability, leading to corrosion, scaling, cloudy water, and skin/eye irritation.

Always correct alkalinity first, then pH. Total alkalinity acts as a buffer that stabilizes pH levels. If you try to adjust pH without proper alkalinity, the pH will bounce around and be difficult to maintain. Once alkalinity is in range, pH adjustments become much easier and more stable.

To raise alkalinity by 10 ppm in a 10,000-gallon pool, add approximately 1.5 pounds (24 oz) of baking soda (sodium bicarbonate). For example, to raise alkalinity from 60 ppm to 100 ppm (40 ppm increase), you would need about 6 pounds of baking soda.

Shocking your pool typically does not significantly lower alkalinity. However, some shock treatments contain acids that may slightly reduce both pH and alkalinity. Calcium hypochlorite shock can actually raise pH slightly. Always test your water after shocking to verify levels.

You can typically swim 20-30 minutes after adding baking soda, once it has fully dissolved and circulated. Run your pump during this time to ensure even distribution. However, it's best to wait until you've retested the water and confirmed the alkalinity is within the safe range.

Yes! Baking soda (sodium bicarbonate) is the main active ingredient in most commercial alkalinity increasers. Using pure baking soda from the grocery store is often more economical. Just make sure it's 100% sodium bicarbonate with no added ingredients.

⚠️ Disclaimer: This calculator provides estimates based on standard chemical concentrations. Actual dosing may vary based on your specific products, water conditions, and other factors. Always read chemical labels carefully and follow manufacturer instructions. Handle pool chemicals with appropriate safety precautions. When in doubt, consult a pool professional.