How to Raise Alkalinity in Pool | The Baking Soda Fix

Raise pool alkalinity by adding sodium bicarbonate (baking soda) while the pump runs, then retest after 6–24 hours to confirm the water lands in the 80–120 ppm range.

For the full breakdown, see our best Alkalinity Increaser For Pools guide.

Low pool alkalinity wrecks water chemistry — pH swings out of control, surfaces corrode, and chlorine stops working. The fix is simple and cheap: pure sodium bicarbonate, which is plain baking soda. Here’s the exact process and the numbers that matter.

What Is Total Alkalinity and Why It Matters

Total alkalinity measures the water’s ability to resist pH changes — it’s a buffer, not a pH reading itself. When alkalinity sits too low, even small additions of acid or chlorine send pH swinging wildly, irritating swimmers’ eyes, eating at pool surfaces, and shortening equipment life.

Most guidance targets 80–120 ppm for home pools. The Pool & Hot Tub Alliance’s public-pool standard allows 60–180 ppm as CaCO₃, but the useful range depends on your sanitizer:

• 80–100 ppm for salt chlorine generators, calcium hypochlorite, lithium hypochlorite, or sodium hypochlorite pools
• 100–120 ppm for sodium dichlor, trichlor, chlorine gas, or bromine pools

ARM & HAMMER’s home pool guidance suggests 110–150 ppm, with anything below 80 ppm needing an immediate raise. Run a salt system? Aim low. Use tablets? Aim higher.

The Baking Soda Method: Exact Dosing and Steps

The standard fix is sodium bicarbonate — sold as baking soda or as any “alkalinity increaser” product, which should be the same chemical. Plain ARM & HAMMER baking soda works fine and costs less than branded pool chemicals.

Before measuring anything, confirm the pool’s actual gallonage, or the math falls apart.

1. Test total alkalinity with a drop-based test kit, not just test strips — strips are fine for monitoring, but a titration kit gives the precise reading you need for dosing.
2. Calculate the dose using your current reading, target ppm, and pool volume. Split large corrections into two or three smaller additions rather than one massive pour.
3. Turn on the pump and let the water circulate. Broadcast the baking soda across the surface, walking the perimeter rather than dumping it in one spot.
4. Wait 6–24 hours before retesting. Retesting sooner gives a false low reading because the powder hasn’t fully dissolved and mixed.
5. Retest and repeat only if needed, adding staged smaller doses until the number lands in range.

Wear gloves and goggles when handling the powder, and skip the job on windy days — airborne baking soda is a mess and a mild irritant. If you run an automated controller, unplug it before adding chemicals and wait at least an hour before restoring power.

Soda Ash vs. Baking Soda: Know the Difference

Soda ash (sodium carbonate) also raises alkalinity, but it pushes pH up far more aggressively than baking soda. Use soda ash only when BOTH pH and alkalinity are low, or when you need a large pH jump. If alkalinity alone is the problem, soda ash risks overshooting pH and leaving you with cloudy water and scale.

Baking soda, by contrast, shifts pH only slightly while doing the real work on alkalinity. When in doubt, choose baking soda — it’s the safer correction for this specific problem.

If you’d rather switch to a purpose-built product, our tested roundup of the best alkalinity increasers for pools compares the top options so you can buy the right one the first time. For most pools, though, a box of plain baking soda gets the job done for a fraction of the price.

Common Mistakes That Ruin the Fix

• Adding too much at once. Overshooting alkalinity makes pH stubbornly hard to correct and can cause scale and cloudiness. Split doses and retest.
• Dumping in one pile. Concentrated powder sitting on the pool floor dissolves slowly and can etch the surface beneath it. Always broadcast around the perimeter.
• Retesting too soon. The water needs hours of circulation for full mixing. A 2-hour retest reads low and tempts you into an unnecessary second dose.
• Skipping circulation. The pump must run continuously during the process, or the chemical settles unevenly.

High alkalinity makes pH nearly impossible to adjust and contributes to scale; low alkalinity causes unstable pH and corrosion. Either way, the fix is the same: test, dose, circulate, wait, retest, then repeat in small steps until you land where your sanitizer wants you.