How to Raise pH in Pool Water Safely

When pool pH is too low, and what low pH does

Raise pH when a reliable test reads below 7.2 for most home pools, and always before it reaches 7.0.

CDC recommends keeping home pool and hot tub water at pH 7.0 to 7.8, a range that balances germ killing, pipe life and swimmer comfort (CDC, page updated May 2024). Below 7.0, CDC says chlorine actually kills germs faster, but pool and hot tub pipes are more likely to corrode or break down. So low pH is mainly an equipment, surface and comfort problem rather than a disinfection failure.

Health department manuals list the damage in plain terms. The Virginia Department of Health guide for operators says low pH etches plaster, corrodes equipment, makes chlorine dissipate rapidly and irritates swimmers’ eyes. The Pennsylvania Department of Health adds excessive chlorine odor and skin irritation below pH 7.2, and recommends running public pools between 7.2 and 7.6.

Low pH is not only a backyard problem. In Sacramento County, inspectors wrote 978 citations for minimum pH at public pools between April 2023 and March 2026, compared with 744 for maximum pH at public pools that get routine health inspections (PC&S analysis of county inspection data). The 2024 Model Aquatic Health Code treats pH below 6.5 as an imminent health hazard that can close a public pool.

Why pool pH keeps dropping

Fixing the cause saves you from adding soda ash every week.

• Rain Rainwater has a pH of nearly 5.75, according to the Pennsylvania DOH, and the Virginia DOH lists rainfall among the things that pull pool pH down.
• Tablet and granular stabilized chlorine Trichlor and dichlor, along with bromine, tend to reduce both pH and alkalinity over time (Pennsylvania DOH). Cyanuric acid stabilizer is on Virginia’s list of pH-lowering substances too.
• Swimmers Urine and other bather waste push pH down (Virginia DOH).
• Gas chlorine and acid overdoses Gas chlorine lowers pH, and so does an over-generous dose of muriatic acid or dry acid used to fix high pH.
• Low total alkalinity When alkalinity is low, Virginia’s guide warns that pH can change dramatically and rapidly with small additions of chemicals or other agents.

Liquid chlorine (sodium hypochlorite) and calcium hypochlorite do the opposite: Pennsylvania’s guidance says they tend to raise pH and alkalinity over time. If your pool switched from tablets to liquid chlorine or a salt system, the pH problem may flip from low to high. Our guide on how to lower pH in pool water covers that side.

Raise alkalinity before you raise pH

Total alkalinity is the buffer that holds pH in place. Every state manual we read says to adjust it first.

Florida’s operators’ manual is direct: because total alkalinity stabilizes pH, “total alkalinity should always be adjusted first,” with 80 to 120 ppm as the most effective range. Virginia’s guide uses the same 80 to 120 ppm range and adds a useful twist: if your pH tends to fall, keep alkalinity in the upper part of the range, but not above 150 ppm.

The tool for alkalinity is sodium bicarbonate (baking soda). Florida and Pennsylvania both publish the same rule of thumb: 1.5 pounds per 10,000 gallons raises total alkalinity about 10 ppm. Knorr Systems, a commercial pool supplier, lists 1.4 pounds for the same change. Virginia’s table below scales it by pool size.

Soda ash vs baking soda vs aeration: which raises pH best

There are three practical ways to push pool pH up, and they do different jobs. Soda ash (sodium carbonate) is the pH mover. It has a pH of about 11.6, roughly three units higher than baking soda’s 8.3 to 8.6, according to Orenda Technologies, a pool chemical maker. Florida DOH notes that baking soda raises alkalinity “without greatly affecting pH,” which is why a pool with low pH but normal alkalinity needs soda ash, not more baking soda.

Aeration raises pH without adding any chemical. Dissolved carbon dioxide forms an acid in water (Virginia DOH), so driving carbon dioxide out with fountains, deck jets, spillways or returns aimed at the surface lets pH climb. Orenda goes further and argues most residential pools without acid feeders do not need soda ash at all because aeration and carbon dioxide loss raise pH on their own. FROG Products makes the same point from the other direction: splashing swimmers break up carbon dioxide and pH rises. Aeration is slow and hard to dose, so it suits a small correction when alkalinity is already in range.

How much soda ash to raise pool pH: dose per 10,000 gallons

Use a health department chart, start with the low end, and retest before adding more.

The clearest public chart we found comes from the Virginia Department of Health’s Portsmouth Health Department guide. It sets the soda ash dose by starting pH and pool size. For a 10,000 gallon pool, a reading of 7.2 to 7.4 calls for 6 oz, 7.0 to 7.2 calls for 8 oz, 6.8 to 7.0 calls for 12 oz and anything below 6.7 calls for 16 oz. At 7.4 to 7.6 the chart says to add nothing.

Knorr Systems publishes a second chart that assumes total alkalinity of 60 to 120 ppm and a target of 7.4. Its doses run higher: 0.75 lb from pH 7.2 and 1.5 lb from pH 6.6 in 10,000 gallons. Knorr also warns not to add more than 1 pound per 10,000 gallons at a time, because larger doses can turn the water milky.

To scale any chart, you need your pool’s real volume. Our pool volume calculator works out gallons from length, width and depth; Florida’s manual uses length x width x average depth x 7.5. As a worked example from the Virginia chart, a 20,000 gallon pool reading 7.1 needs 16 oz of soda ash.

How to raise pH in pool water, step by step

1. Test pH, alkalinity and chlorineCDC recommends a DPD test kit and testing chlorine and pH at least twice per day. A reading under 7.2 is your cue to act.
2. Confirm the gallonsMeasure the pool or use our volume calculator. A wrong volume is the fastest way to overshoot.
3. Fix total alkalinity firstIf alkalinity is under 80 ppm, add baking soda using the table above, circulate, and retest pH before reaching for soda ash.
4. Weigh the soda ashUse the Virginia chart for your starting pH and pool size. Keep each addition at or under 1 lb per 10,000 gallons (Knorr Systems).
5. Pre-dissolve it in a bucket of waterFill a clean bucket with water first, then add the soda ash and stir until dissolved (Knorr Systems). Add chemicals to water, never water to chemicals (Oregon State University’s National Pesticide Information Center).
6. Pour with the pump runningPour it slowly down the side of the pool, near a return if you can, so it disperses (Knorr Systems; FROG Products). Keep everyone out until it has dissolved and dispersed (Virginia DOH); Knorr closes pools for at least 15 minutes.
7. Wait, then retestFROG Products says wait at least 6 hours before retesting; Arm & Hammer suggests 6 to 24 hours for baking soda. Repeat in small steps until pH reads 7.2 to 7.6.
8. Write it downLog the reading, the product and the dose, as Virginia DOH asks public pool operators to do. After a few doses the log shows how far a given amount moves your own pool, which a generic chart cannot.

Rather have a pro balance the water?

Safety rules for soda ash, baking soda and other pool chemicals

Soda ash is strongly alkaline (pH about 11.6, per Orenda), and it goes into a chemical system that may also hold chlorine and acid. CDC’s storage advice applies at home: keep each chemical in its own labeled container, keep it dry, store it below 95 F and away from other chemicals. CDC estimates pool chemical injuries cause about 4,500 emergency department visits a year in the United States (PC&S research on pool injuries).

Public pools face an extra rule: the Model Aquatic Health Code requires pH chemicals to be certified to NSF/ANSI 50 or NSF/ANSI 60. Homeowners are not bound by it, but buying a product that carries one of those marks is an easy way to know what is in the bag.

Troubleshooting: pool pH will not stay up

If soda ash clouds the water, Orenda explains why: the sudden local jump in pH and carbonate pulls calcium carbonate out of solution. It usually settles or redissolves as the filter runs. Our cloudy pool water guide walks through the other causes of haze.

When to stop adjusting and call a pool service

Testing is where most home pools fall down. In a 2020 Water Quality and Health Council survey, 23% of do-it-yourself pool owners said they test chlorine and pH no more often than once every two weeks (PC&S pool hygiene research). CDC’s advice is at least twice per day. If that gap is your gap, a weekly pool cleaning service that tests and doses on every visit is one way to close it. Our pool service cost guide shows what weekly plans charge, and our pool chemical price research tracks what the chemicals themselves cost producers.

Frequently Asked Questions

Related pages