How to Raise pH in Your Pool (The Right Way, With Real Numbers)

Meta Description: Pool pH too low? Here’s exactly how to raise it with soda ash or baking soda, how much to add per gallon, and mistakes that keep it dropping.

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!How to Raise pH in Pool

Your test kit says 6.8. Or maybe 7.0 — close enough to worry. You know your pool should be higher, somewhere in the low 7s, but dumping in random chemicals without knowing what you’re doing is a fast track to bigger problems.

Low pH eats things. Literally. It corrodes metal fixtures, dissolves plaster, destroys heat exchangers, and turns your pool into an expensive chemistry experiment gone wrong.

Here’s how to fix it properly — with specific amounts, not vague advice.

Why Low pH Is a Real Problem

pH measures where your water sits on the acid-to-base scale. Zero is battery acid. Fourteen is drain cleaner. Your pool belongs between 7.2 and 7.6. That’s the range where chlorine works, equipment lasts, and swimmers don’t leave looking like they lost a fight.

Drop below 7.0 and things go sideways fast.

Metal corrosion accelerates. Pool ladders, light fixtures, heater cores, pump impellers — anything metal touching low-pH water corrodes faster. Copper heat exchangers are especially vulnerable. Replacing one costs $800–$1,500. Keeping pH above 7.2? That’s about $3 in soda ash.

Plaster and grout dissolve. Acidic water eats calcium-based surfaces. If your plaster pool looks rough, pitted, or has exposed aggregate in spots, low pH over time is usually what did it. Resurfacing runs $5,000–$10,000. Worth checking your pH.

Chlorine burns off faster. Counterintuitive, but true. Low pH does make chlorine more aggressive — more of it converts to hypochlorous acid. But it’s also less stable. It kills bacteria faster and gets used up faster. You’ll end up adding chlorine way more often.

Eye and skin irritation. Water below 7.0 stings. Red eyes, dry skin, that burning feeling in your nose after swimming. Most people blame chlorine. Nine times out of ten, it’s pH that’s the problem.

Vinyl liner damage. Acidic water pulls plasticizers out of vinyl liners, making them brittle and prone to cracking. A new liner runs $2,000–$4,000 installed. Testing pH? That’s 30 seconds of your time.

What Causes Low pH?

Before you treat it, figure out why it dropped. Otherwise you’re just chasing symptoms.

Rain. Rainwater is naturally acidic — typically between 5.0 and 5.5. A heavy downpour can dump thousands of gallons of acidic water into your pool overnight. After any significant rain, test before you swim.

Heavy swimmer load. Sweat, sunscreen, body oils, and other organic contaminants are acidic. A pool party with 15 people can drop pH noticeably. Not by a ton, but enough to push borderline water into the danger zone.

Over-dosing acid. If you recently lowered pH or alkalinity with muriatic acid and overshot, that’s your answer. Happens more than people admit. Small corrections are always safer than big ones.

CO2 from your surroundings. Pools near heavy vegetation, covered pools with poor ventilation, or pools that rarely get aerated can absorb excess carbon dioxide. CO2 dissolves into water and forms carbonic acid, dragging pH down. Run your jets or a waterfall for a few hours — aeration drives CO2 out and raises pH naturally.

Low alkalinity. Total alkalinity acts as a buffer for pH. When alkalinity drops below 80 ppm, pH becomes unstable — it’ll swing wildly from small changes. Fix alkalinity first, then address pH.

Two Chemicals That Raise pH

You’ve got two options. Both work, but they do different things to your water chemistry. Picking the right one matters.

Soda Ash (Sodium Carbonate)

This is the primary pH-raising chemical for pools. When your pH is low and your alkalinity is fine (or also low), soda ash is the move.

How it works: Soda ash is strongly alkaline. It dissolves in water and directly pushes pH upward. It also raises total alkalinity, but mostly affects pH.

How much to add:

| Pool Size | pH 6.8 → 7.4 | pH 7.0 → 7.4 |

|———–|—————|—————|

| 10,000 gal | 8 oz | 5 oz |

| 15,000 gal | 12 oz | 8 oz |

| 20,000 gal | 16 oz (1 lb) | 10 oz |

| 30,000 gal | 24 oz (1.5 lb) | 16 oz (1 lb) |

These are starting points. Water chemistry isn’t perfectly predictable — your alkalinity, temperature, and other factors all influence how your pool responds. Add the recommended amount, wait 4–6 hours, then retest. You’ll dial it in from there.

How to add it:

1. Dissolve soda ash in a bucket of pool water first. Roughly 1 pound per 2 gallons of water. Stir until dissolved.

2. Pour the solution around the perimeter of the pool with the pump running.

3. Don’t dump it in one spot — concentrated soda ash can cloud the water temporarily and leave white residue on surfaces.

4. Wait at least 4 hours before retesting. Six is better.

Baking Soda (Sodium Bicarbonate)

Baking soda is the go-to when your alkalinity is low but your pH only needs a small bump. It primarily raises total alkalinity with a modest effect on pH.

When to use it: If your alkalinity is below 80 ppm and your pH is between 7.0 and 7.2, baking soda handles both problems at once. If your alkalinity is already 80–120 ppm and pH is the issue, use soda ash instead — baking soda will over-shoot your alkalinity.

How much to add:

To raise alkalinity by 10 ppm, add roughly 1.5 pounds of baking soda per 10,000 gallons.

This will also nudge pH up by about 0.1–0.2 points. Sometimes that’s enough. Sometimes you need soda ash to finish the job.

How to add it: Baking soda is more forgiving than soda ash. You can broadcast it directly across the pool surface with the pump running. It dissolves quickly and doesn’t cloud water like soda ash can. Still, don’t dump 10 pounds in one spot.

The Aeration Trick (Free pH Increase)

Here’s something most pool guides skip: you can raise pH without adding any chemicals at all.

Aeration — running water features, pointing return jets upward to break the surface, or even just running a spa spillover — drives dissolved CO2 out of the water. Less CO2 means higher pH. Simple gas exchange.

When this works great:

• Your pH is slightly low (7.0–7.2) and you just need a small bump
• Your alkalinity is already on the high side and you don’t want to raise it further
• You have a saltwater pool and need pH up but alkalinity is already at 90+

When it won’t cut it:

• pH below 6.8 — you need chemicals for that kind of swing
• Alkalinity is also low — aeration only moves pH, not alkalinity

Run your water feature or pointed-up jets for 24–48 hours and retest. It’s slower than chemicals but free and impossible to overdose.

Step-by-Step: Raise Your Pool pH

1. Test your water. Get readings for pH, total alkalinity, and free chlorine. You need all three to make good decisions. A good test kit — not strips — gives you reliable numbers. The Taylor K-2006 is the industry standard.

2. Check alkalinity first. If alkalinity is below 80 ppm, raise it with baking soda before messing with pH. Low alkalinity makes pH unstable. You’ll just chase it in circles.

3. Calculate your pool volume. Don’t guess. A rectangular pool is length × width × average depth × 7.5 (for gallons). Round or freeform? Use our Pool Chemical Calculator — plug in your dimensions and it does the math.

4. Choose your chemical. pH low + alkalinity low = baking soda first, then soda ash if needed. pH low + alkalinity normal = soda ash.

5. Add the calculated amount. Pre-dissolve soda ash. Broadcast baking soda. Pump running, distributed around the pool.

6. Wait and retest. At least 4 hours for soda ash. Two hours is fine for baking soda. Never add a second dose based on a test taken 30 minutes after treatment.

7. Repeat if needed. Raise pH in increments. Overshooting pH up to 8.0+ creates its own problems — scale buildup, cloudy water, ineffective chlorine. Small corrections are safer.

Common Mistakes (And How to Avoid Them)

Adding too much at once. Overshooting pH is just as bad as leaving it low. Scale forms, water clouds, chlorine stops working right. Add half the calculated amount, test, then add more if you need to.

Not pre-dissolving soda ash. Tossing dry soda ash into the pool creates hot spots of extremely high pH. That’ll bleach vinyl liners, cloud the water for hours, and damage plaster finishes. Take two minutes to dissolve it in a bucket. It’s worth the effort.

Ignoring alkalinity. If your alkalinity is below 60 ppm and you keep adding soda ash for pH, you’ll end up on a pH roller coaster. Alkalinity is the buffer that keeps pH stable. Fix the buffer first.

Testing too soon after treatment. Soda ash needs 4–6 hours to fully circulate and react. Testing at 30 minutes gives you a false reading — usually higher than reality near where you added it, and lower than reality on the far side of the pool.

FAQ