Part of: Pool Chemistry Basics Series

Pool alkalinity too low? How to raise it

Q: What is normal pool alkalinity?

The target range for total alkalinity is 80–120 ppm. Below 80 ppm, pH becomes unstable and can swing sharply from acidic to basic with minor inputs. Above 120 ppm, pH tends to drift upward constantly and is difficult to hold down. Most pools with well-maintained water operate between 90–110 ppm.

Q: Why is my pool alkalinity low?

Low alkalinity has the same root causes as low pH: heavy trichlor tablet use (trichlor is very acidic at pH 2.8), regular dry acid additions, muriatic acid overcorrections, acid rain, and long periods without monitoring. Frequent acid use gradually depletes the alkalinity buffer. If your TA keeps dropping despite raising it, look at what's causing the acidic load — usually trichlor or too-frequent acid additions.

Q: Does raising alkalinity raise pH too?

Yes, modestly. Baking soda raises TA significantly and pH slightly. If pH is also low, baking soda addresses both in one step — which is why it's the preferred fix when both are below target. If pH is in range and you just need to raise TA, baking soda is still the right choice, but retest pH after adding it since there will be a small upward effect.

5 min read · Updated August 5, 2026 · By Jeffrey Thompson

Low total alkalinity is the hidden cause behind pH that won't stay put. Without enough alkalinity, your pH swings wildly — acid rain sends it plummeting, then liquid chlorine sends it shooting back up. The fix is straightforward: baking soda. Here's how much to add, what to expect, and how to keep TA stable going forward.

Quick answer

Target TA: 80–120 ppm. Below 80, add baking soda (sodium bicarbonate) — roughly 1.5 lbs per 10,000 gallons to raise TA by 10 ppm. Broadcast across the pool with the pump running. Wait 4–6 hours and retest before adding more. If pH is also low, baking soda raises both in one step.

What alkalinity does — and why low TA causes problems

Total alkalinity (TA) is your pool's pH buffer. It's the chemical capacity of your water to resist changes in pH. With TA in the right range, a light rain or a dose of liquid chlorine nudges pH by 0.1–0.2 points. With low TA, the same event can swing pH by a full point or more.

Low alkalinity doesn't just make pH hard to manage — it makes your water directly corrosive. Low-TA water is chemically unstable and will attack pool surfaces and equipment to find equilibrium. You get etching on plaster, deterioration of grout, and accelerated wear on metal components.

TA Level	Status	Effect
Below 60 ppm	Very low	Extreme pH instability. Water is corrosive. Fix immediately
60 – 80 ppm	Low	pH bounces. Hard to hold. Surface damage builds over time
80 – 120 ppm	Target range	pH stays stable between test days. No action needed
120 – 150 ppm	Slightly high	pH drifts upward. Harder to keep in range with acid
Above 150 ppm	Too high	pH keeps climbing despite acid additions. Cloudy water risk

How to raise total alkalinity: step by step

Test current TA. A test strip will show the range, but a liquid reagent test kit gives a more accurate reading when you're managing a significant increase
Calculate your dose. Baking soda raises TA about 10 ppm per 1.5 lbs in a 10,000-gallon pool. Use the dose reference below or the baking soda calculator
With the pump running, broadcast baking soda across the pool surface. Don't pour it in one concentrated spot — walk it across the pool for even distribution
Wait 4–6 hours with the pump circulating before retesting. Baking soda dissolves and mixes more slowly than some other chemicals
Retest, then decide on a second dose. If TA is still below 80, add another round. You can safely add two doses per day — but retesting between doses gives you a more accurate picture of where you are

When TA is very low (below 60 ppm)

Very low alkalinity is a multi-step correction, not a one-dose fix. The math may call for several pounds of baking soda, but adding it all at once can temporarily cloud the water and makes it harder to track where TA actually lands. Add in 2–3 doses over a day or two, retesting between each. pH will also climb as you raise TA — retest both parameters after each dose.

Baking soda dose reference

Approximate amount of baking soda needed to raise TA (10,000-gallon pool):

Current TA	Target TA	Baking Soda (10k gal)	Baking Soda (20k gal)
40 ppm	100 ppm	~9 lbs	~18 lbs
60 ppm	100 ppm	~6 lbs	~12 lbs
70 ppm	100 ppm	~4.5 lbs	~9 lbs
80 ppm	100 ppm	~3 lbs	~6 lbs

These are estimates based on 1.5 lbs per 10 ppm per 10,000 gallons. Actual results vary with water chemistry and temperature. Always retest before a second dose rather than adding the full calculated amount at once.

Free Calculator

Baking Soda Calculator

Enter your pool volume, current TA, and target — get the exact pounds of baking soda to add.

Use the calculator →

What causes low alkalinity?

TA drops for the same reasons pH drops — acidic inputs into your water deplete the buffer over time:

Trichlor tablets: Very acidic (pH ~2.8). Regular tablet use continuously depletes both alkalinity and pH. Heavy trichlor users often find themselves chasing low TA as a recurring problem
Muriatic acid or dry acid: Every acid addition lowers TA. If you're adding acid frequently to control high pH, check whether high alkalinity is driving that pH drift — if so, using acid directly on TA first may reduce how much acid you end up adding overall
Acid rain and heavy rain: Rain typically has a pH of 5–6. Repeated rain events can gradually erode TA, especially in smaller pools
CO2 from algae: During an algae bloom, CO2 production can push TA down along with pH
Dilution: If your fill water has low alkalinity, topping off a pool repeatedly can dilute TA over a season

Low alkalinity pool: symptoms to watch for

Low TA doesn't always announce itself directly. The more visible symptoms are:

pH that won't hold: You test Monday at 7.2, add soda ash, get to 7.5, test Thursday and it's back at 7.1. This bounce cycle is the signature of insufficient alkalinity
Eye and skin irritation: Low pH (from unstable TA) causes burning eyes and irritated skin in swimmers
Surface etching: Over time, a low-TA pool becomes corrosive. Plaster feels rough, pebble surfaces begin to deteriorate, and grout dissolves at the waterline
Metal staining: Corrosive water pulls metal ions from equipment into the water, leaving copper or iron stains on walls and floors

Alkalinity vs pH: fix TA first

If both TA and pH are low, the fix order matters:

Raise TA first with baking soda. Wait 4–6 hours and retest
Recheck pH. Raising TA with baking soda also raises pH slightly — pH may have come up on its own. If it's still below 7.4, add a small dose of soda ash
Don't add soda ash while TA is still low. Without the TA buffer, pH will bounce right back down regardless of what you add

Baking soda vs soda ash

Both are used to raise pH, but they work differently. Baking soda (sodium bicarbonate) primarily raises alkalinity, with a modest lift to pH. Soda ash (sodium carbonate) primarily raises pH, with a smaller effect on TA. Use baking soda when TA is low; use soda ash when TA is in range but pH is low. The full comparison guide explains the differences in detail.

PoolChem Tracker tracks both TA and pH readings over time. If your TA has been trending down for weeks, you'll see it in the chart — before it becomes a problem. Download free →

Keeping alkalinity stable long-term

Once you've raised TA into range, keeping it there is mostly about managing what lowers it:

If you're on trichlor tablets and fighting chronic low TA, switching to liquid chlorine will reduce the acidic load substantially
When using muriatic acid, dose conservatively and retest — overdosing acid is the fastest way to deplete TA
Test TA at least every two weeks. Small corrections are easier than recovering from a large deficit
After heavy rain, retest and add baking soda as needed — don't wait for the bounce cycle to start

Catch TA drift before it causes problems

PoolChem Tracker tracks alkalinity with every reading and recommends the exact amount of baking soda when TA drops below target. No charts, no manual math.

Frequently asked questions

How do I raise pool alkalinity?

Add baking soda (sodium bicarbonate) with the pump running. Broadcast it across the pool surface rather than pouring it in one spot. A starting-point dose: 1.5 lbs per 10,000 gallons to raise TA by 10 ppm. Wait 4–6 hours and retest before adding more. Use the free baking soda calculator for the exact dose based on your pool volume and current reading.

What is normal pool alkalinity?

The target range is 80–120 ppm. Below 80 ppm, pH becomes unstable and bounces with minor chemical or weather events. Above 120 ppm, pH tends to drift upward despite acid additions. Most well-maintained pools sit at 90–110 ppm, with acid additions keeping the upper bound in check.

Why is my pool alkalinity low?

Low TA typically comes from acidic inputs: trichlor tablets (pH ~2.8), regular acid additions, rain, or an algae event. If you're on tablets and TA keeps dropping, that's the tablets doing it. Switching to liquid chlorine significantly reduces the acidic load on your water chemistry. Test after rain events — they're often the trigger for TA dropping below 80.

Does raising alkalinity raise pH too?

Yes, modestly. Baking soda raises TA primarily and pH slightly. If both TA and pH are low, baking soda addresses both in one step — which is exactly why it's the preferred fix when both are below target. After raising TA, retest pH before deciding whether to add soda ash. In many cases, TA in range means pH follows without a separate treatment.