Ever stare at your pool test kit results and feel completely lost? You’re not alone. After helping thousands of pool owners over the past 15 years, I’ve seen this frustration countless times. Your pH won’t stabilize, your alkalinity keeps dropping, and you’re stuck in a cycle of adding chemicals that never seem to work.

Let me share what I’ve learned from maintaining pools professionally and teaching water chemistry to homeowners. Getting your alkalinity right isn’t just about dumping in chemicals. It’s about understanding what’s happening in your water and why.

Understanding pH and Alkalinity: The Foundation of Pool Chemistry

What is pH and Why Should You Care?

pH measures whether your pool water is acidic or basic, on a scale from 0 to 14. Your pool needs to sit between 7.4 and 7.6 for optimal comfort and equipment protection.

When I first started managing commercial pools, I learned this lesson the hard way. A facility I worked with had persistent cloudy water and complaints about skin irritation. The culprit? High pH at 8.2. Once we brought it down to 7.5, the chlorine started working properly again, and the complaints stopped within days.

Here’s what happens with unbalanced pH:

High pH (above 7.8): Your chlorine loses effectiveness. I’ve tested pools with perfect chlorine readings that still had algae problems because the pH was too high for the chlorine to work.
Low pH (below 7.2): Your water becomes corrosive. I’ve seen heater elements fail prematurely and vinyl liners develop wrinkles from acidic water eating away at the material.

What is Total Alkalinity and How Does It Work?

Total alkalinity is your pH’s stabilizer. Think of it as shock absorbers on a car. Without them, every bump sends you flying. Without proper alkalinity, every raindrop or swimmer sends your pH bouncing wildly.

The ideal range is 80 to 120 parts per million (ppm). I typically aim for 100 ppm in most pools because it provides the best buffer without pushing pH too high.

The Dance Between pH and Alkalinity

These two measurements work together constantly. After testing hundreds of pools, I’ve noticed a pattern: when alkalinity drops below 60 ppm, pH becomes nearly impossible to control. You can add pH increaser, but within days, the pH has crashed again.

That’s why the order matters. Always adjust alkalinity first, then pH, and finally chlorine. This sequence saved me countless hours of frustration and wasted chemicals.

Why Pool Chemistry Feels Like Fighting a Losing Battle

The Real Reasons Your Levels Keep Changing

During my years managing resort pools, I tracked what affected water chemistry most. Here’s what I found:

Rain is a major culprit. A single thunderstorm can drop your alkalinity by 20 ppm or more. Rainwater is naturally acidic (around 5.6 pH), and when it dilutes your pool, it throws everything off balance.

Swimmers themselves change your chemistry. At a community pool I maintained, we could predict chemistry changes based on attendance. A busy weekend with 50+ swimmers would consistently drop pH and alkalinity more than a quiet weekday with five swimmers.

Organic debris matters too. Leaves, grass clippings, and pollen introduce acids that consume your alkalinity buffer.

Why pH Changes So Quickly

pH is volatile by nature. It reacts to carbon dioxide in the air, chlorine additions, and even the time of day. I test my own pool twice weekly during summer because pH can shift significantly between tests.

This is why catching problems early matters. Small adjustments are easier and cheaper than major corrections.

The Critical Sequence for Chemical Adjustments

Why Order Matters (And What Happens When You Get It Wrong)

I learned this principle from a pool chemistry instructor who had 30 years of experience. He showed us two pools side by side. Both had low pH and low alkalinity.

Pool A: Owner added pH increaser first. The pH rose temporarily, then crashed two days later because nothing was stabilizing it.

Pool B: Owner added alkalinity increaser first, waited, then adjusted pH. The levels stayed stable for two weeks.

The difference? Alkalinity provides the foundation. Without it, any pH adjustment is temporary.

My Testing Schedule Recommendation

Based on managing both residential and commercial pools:

Test twice weekly during swimming season
Test once weekly during off-season
Test after heavy rain, parties, or chemical additions
Test before adding any chemicals

I use both test strips for quick checks and a liquid test kit (Taylor K-2006) for accuracy when making adjustments.

The Chemicals You Need to Raise Alkalinity

Alkalinity Increaser (Sodium Bicarbonate)

This is your primary tool for raising alkalinity. The pool store version and the big box of baking soda from the grocery store contain the same active ingredient: sodium bicarbonate.

I’ve used both extensively. Here’s my honest assessment: baking soda costs about 60% less. A 13.5-pound bag of alkalinity increaser runs around $15-20, while an equivalent amount of baking soda costs $6-8.

The only difference? Grain size. Pool store products dissolve slightly faster, but if you’re patient and let your pump run for 30 minutes, baking soda works identically.

How Alkalinity Increaser Affects Your Pool

When you add sodium bicarbonate, it raises alkalinity significantly and pH slightly. In my testing, adding enough to raise alkalinity by 10 ppm typically increases pH by 0.1 to 0.2 units.

This is manageable and expected. You’ll fine-tune the pH after alkalinity stabilizes.

Understanding pH Adjusters

While we’re focused on alkalinity, you’ll likely need these too:

pH Increaser (Soda Ash/Sodium Carbonate): Raises pH primarily, alkalinity slightly. Use this after alkalinity is in range but pH is still low.

pH Decreaser (Sodium Bisulfate): Lowers both pH and alkalinity. This is what you’ll use if both are too high.

I keep all three chemicals on hand because pool chemistry rarely needs just one adjustment.

Step-by-Step: How I Raise Alkalinity in Pools

Step 1: Test Your Current Levels

Use a reliable test kit. I can’t stress this enough after seeing homeowners waste money on chemicals because their cheap test strips gave inaccurate readings.

Record your results:

Current alkalinity: _____ ppm
Current pH: _____
Pool volume: _____ gallons

Step 2: Calculate How Much to Add

Here’s the formula I use:

To raise alkalinity by 10 ppm in 10,000 gallons, add 1.5 pounds of sodium bicarbonate

For a 20,000-gallon pool with alkalinity at 60 ppm (needing to reach 100 ppm), you’d need:

40 ppm increase needed
20,000 gallons ÷ 10,000 = 2
1.5 pounds × 4 (for 40 ppm) × 2 (for pool size) = 12 pounds of sodium bicarbonate

I usually add half the calculated amount, retest, then add more if needed. This prevents overshooting.

Step 3: Add the Chemical Properly

Turn on your circulation system. This is non-negotiable. I’ve seen stains on pool surfaces from chemicals settling in one spot.

Walk around the pool perimeter, broadcasting the sodium bicarbonate across the water surface. Don’t dump it all in one location.

For large amounts (over 5 pounds), I divide it into two applications several hours apart.

Step 4: Wait and Retest

This is where patience pays off. Wait at least 6 hours, preferably overnight, for the chemical to fully circulate and dissolve. The water needs time to reach equilibrium.

I typically add alkalinity increaser in the evening, let the pump run overnight, and test the next morning.

Step 5: Adjust pH if Needed

After alkalinity stabilizes, check your pH. If it’s still below 7.4, you have two options:

Option A: Add pH increaser (soda ash) following product directions.
Option B: Run water features (waterfall, fountain, jets) to aerate the water naturally. This raises pH without affecting alkalinity.

I prefer aeration when pH is only slightly low (7.2 to 7.3) because it’s free and effective.

Balancing Both Levels: Real-World Scenarios

Scenario 1: Low pH and Low Alkalinity

This is the most common situation I encounter, especially after rain.

My approach: Add alkalinity increaser first. In most cases, this alone brings both values close to range. If pH is still low after alkalinity stabilizes, aerate the water or add a small amount of pH increaser.

Example from my experience: A 15,000-gallon pool with alkalinity at 50 ppm and pH at 7.0. I added 9 pounds of baking soda. Next day, alkalinity read 95 ppm and pH was 7.3. I ran the waterfall for 4 hours, and pH rose to 7.5. Perfect.

Scenario 2: Low pH with Normal Alkalinity

This happens frequently with pools using chlorine tablets, which are acidic.

My approach: Add pH increaser or aerate the water. Don’t touch the alkalinity since it’s already in range.

I encountered this with a client who used trichlor tablets in a floating dispenser. We switched to a slower-dissolving tablet and added an aerating return jet, which solved the chronic low pH problem.

Scenario 3: Low pH and High Alkalinity

This tricky situation requires a two-step process.

My approach: Add pH decreaser to lower both alkalinity and pH. Then, once alkalinity is in range, use aeration to raise pH back up without affecting alkalinity.

This scenario taught me patience. You can’t rush it by adding both pH decreaser and increaser simultaneously. That’s just wasting chemicals.

Scenario 4: Normal pH with Low Alkalinity

Straightforward fix.

My approach: Add alkalinity increaser. Monitor pH over the next few days. If it rises above 7.8, you may need a small amount of pH decreaser.

Scenario 5: Normal pH with High Alkalinity

I see this in pools where owners have been fighting cloudy water and kept adding “clarifiers” that actually increased alkalinity.

My approach: Add pH decreaser to bring alkalinity down. Then aerate the water if pH drops too low.

Scenario 6: High pH and Low Alkalinity

My approach: Add pH decreaser first to lower the pH, then add alkalinity increaser to stabilize it. This prevents the pH from bouncing back up immediately.

Scenario 7: High pH with Normal Alkalinity

Common in pools with waterfalls or salt systems.

My approach: Add pH decreaser. Monitor alkalinity, and if it drops below 80 ppm, add a small amount of alkalinity increaser.

Scenario 8: High pH and High Alkalinity

My approach: Add pH decreaser. This lowers both measurements simultaneously. Keep testing every 12 hours until both reach the ideal range.

Why Your pH Won’t Stay Balanced: Common Causes

Water Features and Aeration

I manage several pools with elaborate waterfalls. Every single one has consistently higher pH than pools without features.

Why? Aeration releases carbon dioxide from the water, which raises pH. The more your water splashes and moves, the higher your pH climbs.

My solution: Reduce waterfall runtime or add pH decreaser weekly. I typically add 1-2 pounds of pH decreaser weekly to high-aeration pools.

Salt Water Chlorine Generators

Salt systems produce chlorine through electrolysis, which creates sodium hydroxide as a byproduct. This raises pH consistently.

I worked with a saltwater pool owner who was adding pH decreaser twice weekly and couldn’t understand why. Once I explained it was the salt system, not poor water balance, she adjusted her maintenance routine and saved money on unnecessary testing.

My solution: Expect to add pH decreaser regularly. This is normal, not a problem. Some owners reduce salt system runtime, but watch your chlorine levels carefully if you do this.

Chlorine Type Matters

Different chlorines affect pH differently:

Liquid chlorine (sodium hypochlorite): Raises pH significantly. I’ve seen pH jump from 7.4 to 8.0 after a shock treatment with liquid chlorine.

Calcium hypochlorite (cal hypo): Raises pH moderately. Less impact than liquid chlorine but still noticeable.

Trichlor tablets: Lower pH over time. Pools using only tablets often struggle with low pH and need pH increaser regularly.

My solution: Understand what your sanitizer does to pH and plan accordingly. I often recommend alternating between cal hypo for shock treatments and trichlor for daily sanitization to balance the pH effects.

Heavy Bather Load

More swimmers mean more pH fluctuation. Body oils, sweat, sunscreen, and other organic contaminants are typically acidic.

At a pool I managed that hosted swim lessons, we tested pH before and after each session. With 20 kids in the water for an hour, pH would drop by 0.2 to 0.3 units consistently.

My solution: Test pH more frequently during periods of heavy use. A busy pool party weekend means checking chemistry before and after.

Environmental Factors

Rain, leaves, and grass clippings all affect pH. Rain is naturally acidic. Decomposing organic matter produces acids that consume your alkalinity buffer.

My solution: Test after storms and remove debris promptly. I skim my pool daily during fall because leaves can lower pH by 0.5 units within days if left in the water.

Troubleshooting Persistent Alkalinity Problems

Alkalinity Keeps Dropping

If you’re constantly adding alkalinity increaser, something is consuming it faster than normal. Based on my experience, the usual suspects are:

Heavy rainfall: Test your rainwater pH if you’re curious. Mine typically measures 5.2 to 5.8, which explains why alkalinity drops after storms.

Trichlor tablets: These are very acidic and consume alkalinity over time. If you use them heavily, expect to add alkalinity increaser monthly.

Acidic debris: Pine needles are particularly acidic. Pools surrounded by pine trees need more alkalinity maintenance.

Alkalinity Won’t Stay in Range

This usually means your fill water has issues. I once helped a homeowner whose well water had naturally low alkalinity (25 ppm). Every time he added water, it diluted his pool’s alkalinity.

My solution: Test your source water. If it’s low in alkalinity, factor this into your maintenance routine. You’ll need more alkalinity increaser than pools filled with city water that typically has 100+ ppm alkalinity.

My Final Recommendations for Pool Owners

After years of maintaining pools and teaching others, here’s what I’ve learned works:

Keep good records: I use a simple notebook to track test results and chemical additions. This helps me spot patterns and predict problems.

Don’t skip testing: Even clear water can have unbalanced chemistry. I’ve tested beautiful-looking pools with pH at 8.2 and alkalinity at 40 ppm.

Buy quality chemicals: I’m all for saving money with baking soda, but don’t compromise on test kits. A reliable test kit ($50-70) pays for itself in prevented mistakes.

Be patient: Water chemistry takes time to stabilize. Adding more chemicals because you don’t see immediate results usually makes things worse.

Learn your pool’s patterns: Every pool is unique. My pool consistently needs alkalinity increaser after heavy rain but stays stable otherwise. Knowing this helps me maintain it proactively.

Conclusion

Raising alkalinity in your swimming pool doesn’t require a chemistry degree, but it does require understanding how alkalinity and pH work together. After maintaining hundreds of pools over 15 years, I can tell you the formula for success is simple: test regularly, adjust alkalinity first, then pH, and be patient with the process.

The frustration you feel when chemistry won’t balance is something every pool owner experiences. The difference between struggling and succeeding is understanding why you’re adding chemicals, not just dumping them in and hoping for the best.

Start with your alkalinity. Get it stable between 80 and 120 ppm. Then fine-tune your pH. Follow this sequence every time, and you’ll spend less time fighting water chemistry and more time enjoying your pool.

How to Increase Alkalinity in a Swimming Pool?