How to Raise Pool Alkalinity (And Why It Matters More Than pH)

Low total alkalinity (under 80 ppm) is the hidden cause of wildly swinging pH. Fix alkalinity first and chemistry stabilizes — then everything else is easier.

What alkalinity does

Total alkalinity (TA) is the pool's pH buffer. Without it, every rain, every swimmer, every chemical addition makes pH swing erratically. Ideal range: 80–120 ppm. Under 80 ppm, pH becomes unmanageable; over 120 ppm, it locks high and scaling begins.

How to raise alkalinity

The chemical is sodium bicarbonate — plain baking soda. Same thing you buy at Costco. Pool-store “alkalinity increaser” is the same product at 3x the price.

1. Test current TA. Target 100 ppm.
2. Rule of thumb: 1.5 lbs of sodium bicarbonate per 10,000 gallons raises TA by 10 ppm.
3. For a 20,000 gal pool needing to go from 60 ppm to 100 ppm: 40 ppm × 3 lbs = 12 lbs baking soda.
4. Add slowly, broadcasting across the pool with pump running.
5. Wait 6 hours for circulation, retest.

Why low alkalinity keeps happening

• Heavy rain dilution (South Florida summer thunderstorms)
• Over-acidifying (too much muriatic acid for pH correction)
• Topping up pool with soft water
• Saltwater pools with aggressive acid dosing systems

Order of operations for chemistry

When balancing a pool from scratch, this is the order:

1. Alkalinity first — target 80–120 ppm
2. pH second — target 7.4–7.6
3. Calcium hardness third — target 250–400 ppm
4. Cyanuric acid fourth — target 30–50 ppm (or 60–80 salt)
5. Free chlorine last — target 2–4 ppm

Trying to fix chemistry out of order is why most DIY pool owners get stuck.

Part of our South Florida pool chemistry series. Let our techs handle chemistry weekly so you never have to do this math.

Frequently Asked Questions