Pool alkalinity increaser and test kit on a daylight equipment pad

How To Raise Pool Alkalinity

Total alkalinity below 80 ppm causes pH to swing wildly, makes water aggressive enough to etch plaster, and gives chlorine an unstable baseline. Raising alkalinity is straightforward chemistry — sodium bicarbonate (the active ingredient in baking soda and pool alkalinity increaser) raises alkalinity reliably without much effect on pH. Here’s how to do it correctly.

Why alkalinity matters more than you think

Total alkalinity is the buffer that keeps pH stable. It’s measured in ppm of calcium carbonate equivalent, and the target range for residential pools is 80–120 ppm. Outside that range:

  • Below 80 ppm: pH bounces. You add acid; pH crashes too low. You add base; pH spikes too high. Chlorine effectiveness becomes erratic. Plaster surfaces etch over months.
  • Above 120 ppm: pH locks high (typically 7.8+). Scale forms on tile, salt cell plates, and heater elements. Chlorine becomes less effective.

What you’ll need

  • A liquid drop test kit
  • Pool alkalinity increaser (sodium bicarbonate)
  • A 5-gallon bucket (optional, for slurry mixing on larger doses)
  • The pump running

Calculate the dose

The standard dose: 1.5 lb of sodium bicarbonate per 10,000 gallons raises alkalinity by 10 ppm. So if your alkalinity is 50 ppm and you want to reach 100 ppm in a 20,000 gallon pool:

50 ppm rise × (20,000 / 10,000) × 1.5 = 15 lb of alkalinity increaser

Add no more than 10 lb at a time. Wait 6–8 hours of pump circulation between doses and retest.

Step-by-step

1Test both alkalinity and pH first.

If pH is also low, alkalinity increaser will gently raise pH as a side effect, which is desirable. If pH is high, you may need to use acid to bring pH down first before raising alkalinity.

2Walk around the perimeter, sprinkling the increaser into deep water.

For small doses (under 5 lb), you can sprinkle the dry powder directly into the pool. Pour in front of return jets so current disperses it. Avoid pouring it all in one spot — concentrated alkalinity briefly raises localized pH.

3For larger doses, pre-mix as a slurry.

Mix the dry powder into a 5-gallon bucket of pool water until dissolved. Pour the solution slowly around the perimeter. This ensures even distribution and faster mixing.

4Run the pump 6–8 hours, then retest.

Alkalinity changes take time to fully equilibrate — retest before adding any more. The biggest cause of over-shooting alkalinity is impatience.

Chemicals at PST

Durachlor 5 lb total alkalinity increaser

Durachlor Total Alkalinity Increaser

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Taylor K-2006 pool water test kit

Taylor K-2006 Test Kit

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Durachlor pH Down reducer

Durachlor pH Down (if needed)

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Baking soda hack: grocery-store baking soda is the same chemical as pool alkalinity increaser. It works fine, just slower to dissolve. The 5 lb pool product is more cost-effective per pound for serious adjustments, but if you’re only nudging up 10–20 ppm, baking soda from the grocery store is a fair substitute.

For pH balance and chemistry strategy across all six parameters, see our pool chemical levels guide.

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