How to Raise Pool Alkalinity: Complete Step-by-Step Guide

Tools & Supplies Needed

Find on Amazon: Taylor K-2006 Pool Test Kit , Pure Sodium Bicarbonate , Digital Pool Water Tester

Quick Answer

Low alkalinity is one of the most common pool chemistry issues, and fortunately, it's straightforward to fix. You'll need to add sodium bicarbonate (baking soda) to your pool water. The standard dosage is approximately 1.5 pounds of sodium bicarbonate per 10,000 gallons of pool water to raise total alkalinity by 10 ppm. Always test your current alkalinity level first and add chemicals gradually to avoid overshooting your target range.

Understanding Pool Alkalinity

Total alkalinity (TA) acts as a pH buffer in your pool water, preventing dramatic pH swings that can cause equipment damage, swimmer discomfort, and chlorine inefficiency. For traditional chlorine pools, maintain alkalinity between 80-120 ppm. For salt water generator pools, target the lower range of 60-80 ppm to prevent excessive pH rise that SWG systems naturally cause.

Low alkalinity symptoms include:

• pH that bounces up and down frequently
• Difficulty maintaining stable chlorine levels
• Etching on plaster surfaces
• Corrosion of metal pool equipment
• Eye and skin irritation for swimmers

Testing Your Current Alkalinity Level

Before adding any chemicals, you must know your starting point. Use a reliable test kit like the Taylor K-2006 or comparable digital tester. Pool store test strips are notoriously inaccurate for alkalinity readings, so invest in proper liquid reagent testing.

Test your water when the pool has been circulating for at least 30 minutes and hasn't been used for swimming in the past hour. Take your sample from elbow-deep water, away from return jets and skimmers. Record both your pH and alkalinity readings, as you'll likely need to adjust both.

Step-by-Step Alkalinity Raising Process

1. Calculate the required amount: Determine how much sodium bicarbonate you need. Use this formula: (Target TA - Current TA) × Pool Volume ÷ 10 × 1.5 = Pounds of sodium bicarbonate needed. For example, if your 20,000-gallon pool has 60 ppm TA and you want 100 ppm: (100-60) × 20,000 ÷ 10 × 1.5 = 12 pounds of sodium bicarbonate.
2. Prepare your equipment: Ensure your pool pump is running and will continue running for at least 6 hours. Have your measuring container and any mixing tools ready.
3. Add sodium bicarbonate gradually: Never dump all the chemical in one spot. Walk around the pool perimeter, broadcasting the sodium bicarbonate evenly across the surface. Add no more than 2 pounds per 10,000 gallons at one time to prevent cloudiness.
4. Allow circulation: Let the pump run for at least 6 hours to fully dissolve and distribute the chemical. Sodium bicarbonate dissolves relatively slowly, so patience is essential.
5. Retest and repeat: After 6-8 hours, retest your alkalinity. If you haven't reached your target range, repeat the process with the remaining calculated amount.
6. Address pH if necessary: Sodium bicarbonate will raise both alkalinity and pH. If your pH rises above 7.6, you'll need to lower it with muriatic acid after achieving your target alkalinity.

Chemical Options and Considerations

Sodium Bicarbonate (Baking Soda): The most common and cost-effective option. Pure baking soda from the grocery store works identically to pool-branded alkalinity increasers at a fraction of the cost. Arm & Hammer baking soda is chemically identical to expensive pool store alternatives.

Sodium Carbonate (Soda Ash): Primarily raises pH but will increase alkalinity slightly. Not recommended as the primary alkalinity raiser because it raises pH more dramatically than alkalinity.

Sodium Sesquicarbonate: A combination product that raises both pH and alkalinity more gradually than straight sodium carbonate. More expensive but can be useful in specific situations.

Dosing Guidelines by Pool Size

• 10,000 gallons: 1.5 lbs sodium bicarbonate = +10 ppm alkalinity
• 15,000 gallons: 2.25 lbs sodium bicarbonate = +10 ppm alkalinity
• 20,000 gallons: 3 lbs sodium bicarbonate = +10 ppm alkalinity
• 25,000 gallons: 3.75 lbs sodium bicarbonate = +10 ppm alkalinity
• 30,000 gallons: 4.5 lbs sodium bicarbonate = +10 ppm alkalinity

Common Mistakes to Avoid

Adding too much at once: Excessive sodium bicarbonate can cause temporary cloudiness and make pH adjustments more difficult. Always add gradually over multiple treatments if needed.

Ignoring pH levels: Raising alkalinity will also raise pH. Monitor both parameters and be prepared to lower pH with muriatic acid if it exceeds 7.8.

Not running the pump long enough: Sodium bicarbonate needs adequate circulation time to dissolve completely. Insufficient mixing leads to inaccurate test results and potential localized high-alkalinity spots.

Using the wrong chemical: Don't confuse sodium bicarbonate with sodium carbonate (soda ash). While both are alkaline, they have very different effects on pH versus alkalinity ratios.

Prevention and Maintenance

Regular testing and small adjustments prevent major alkalinity swings. Test weekly during swimming season and adjust as needed with small amounts of sodium bicarbonate. Factors that commonly lower alkalinity include heavy rainfall, high bather loads, and certain sanitizer systems.

For salt water pools, expect to add alkalinity increaser more frequently due to the natural pH rise caused by chlorine generation, which often requires muriatic acid additions that gradually lower alkalinity over time.