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Baking Soda vs Soda Ash: When to Use Bicarbonate or Carbonate

Baking soda (sodium bicarbonate) and soda ash (sodium carbonate) look nearly identical. Both are white crystalline powders derived from mineral trona deposits, and both raise chemical parameters in swimming pools. However, using the wrong chemical is one of the most common mistakes pool owners make. Pouring baking soda when you need soda ash will spike your alkalinity while leaving pH acidic, while dumping soda ash when you need baking soda can turn your pool into a cloudy, scale-forming mess. Calculate your doses with our pool alkalinity calculator and pool pH calculator.

9 min read, updated September 2026

Key takeaways

  • Baking soda (sodium bicarbonate) has a natural pH of 8.3 and primarily raises total alkalinity.
  • Soda ash (sodium carbonate) has a natural pH of 11.4 and dramatically raises pH with less effect on alkalinity.
  • Use baking soda when alkalinity is below 80 ppm and pH is relatively stable.
  • Use soda ash when pH has crashed below 7.2 and alkalinity is already in a healthy range.

Chemical Comparison: Sodium Bicarbonate vs Sodium Carbonate

The difference between baking soda and soda ash comes down to a single hydrogen atom and a single sodium atom. Baking soda has the chemical formula NaHCO3 (sodium bicarbonate). Soda ash has the chemical formula Na2CO3 (sodium carbonate). This small difference changes how each chemical reacts in water.

When dissolved in pure water, baking soda produces a solution with a pH of roughly 8.3. Because 8.3 is relatively close to a pool's ideal pH range (7.4 to 7.6), baking soda adds substantial bicarbonate buffer capacity without moving pH very far. In contrast, soda ash produces a solution with a caustic pH of 11.4. Adding even a small amount of soda ash introduces strong hydroxide and carbonate ions that drive pH upward quickly.

Chemical Comparison: Baking Soda vs Soda Ash for Swimming Pools

AttributeBaking Soda (Sodium Bicarbonate)Soda Ash (Sodium Carbonate)Pool Store Equivalent
Chemical FormulaNaHCO3Na2CO3Alkalinity Up vs pH Up
Natural pH in Solution8.3 (Mildly basic)11.4 (Strongly basic)Varies by blend
Primary EffectRaises Total AlkalinityRaises Water pHTargeted dosing
Effect on Other ParameterVery minor rise in pHModerate rise in AlkalinityLinked buffer reaction
Grocery Store Cost$0.80 to $1.20 per lb$1.50 to $2.50 per lb (Washing soda)Often 2x markup in pool store
Solubility in Cold WaterDissolves rapidly without heatCan clump; can cause cloudinessPre-dissolving recommended

The Decision Matrix: Which One Does Your Pool Need?

Before adding either chemical, test both pH and total alkalinity. Use this decision matrix to pick the right treatment:

  • Low Alkalinity (under 80 ppm) and Low pH (under 7.2): Add soda ash first. It will correct the low pH quickly while providing a moderate lift to alkalinity. Retest after 6 hours, then use baking soda if alkalinity needs an extra boost.
  • Low Alkalinity (under 80 ppm) and Normal pH (7.4 to 7.6): Add baking soda. It will lift total alkalinity to the 90 to 110 ppm target while nudging pH up only slightly.
  • Normal Alkalinity (80 to 120 ppm) and Low pH (under 7.2): Use soda ash in small increments, or aerate the water by running waterfalls and spa jets to raise pH naturally without adding any alkalinity.
  • High Alkalinity (over 130 ppm) and Low pH (under 7.2): Never use baking soda. Aerate the pool to bring pH up to 7.4 without raising alkalinity.

Baking Soda Dosing Rule: 1.5 pounds per 10,000 gallons raises Total Alkalinity by roughly 10 ppm.

Soda Ash Dosing Rule: 6 ounces per 10,000 gallons raises pH by roughly 0.2 units.

Can You Use Grocery Store Baking Soda in Your Pool?

Yes. Food-grade baking soda purchased in bulk bags from a warehouse store or grocery store is 100 percent pure sodium bicarbonate. It is chemically identical to products sold in pool supply stores labeled as alkalinity increaser or alkalinity plus, but it typically costs half the price. Just verify that the package contains pure sodium bicarbonate with no added scents, cornstarch, or cleaning additives. Calculate your dose using our pool alkalinity calculator.

baking soda vs soda ash pool FAQs

Can baking soda clear cloudy pool water?

Baking soda will only clear cloudy water if the cloudiness was caused by extremely low alkalinity or erratic pH swings. If cloudiness is caused by algae, poor filtration, or dead organic matter, baking soda will not clear the water. In fact, adding too much baking soda can cause calcium to precipitate, making the water cloudier.

Can I use washing soda instead of pool soda ash?

Yes. Arm & Hammer Super Washing Soda is 100 percent sodium carbonate, which is the exact same active ingredient found in pool store pH increaser. As with baking soda, verify that the box lists only sodium carbonate without fragrance or optical brighteners.

How long should I wait between adding baking soda and chlorine?

Wait at least 20 to 30 minutes with the circulation pump running after adding baking soda before adding liquid chlorine. While they do not produce a dangerous reaction, adding chemicals simultaneously can cause localized high pH that reduces chlorine effectiveness.

Will baking soda raise pool pH if I add enough of it?

Baking soda will raise pH slightly, but because its own pH in solution is only 8.3, it hits a natural ceiling. If your pH is 7.0 and you add 20 pounds of baking soda, your pH will rise to about 7.5 to 7.6, but your alkalinity will spike to 200+ ppm, creating severe balance issues.