Pool Chemistry Basics: The Ideal Levels Chart
Ideal pool chemistry levels in one chart: pH, free chlorine, alkalinity, calcium, stabilizer and salt, plus what to adjust first and a volume calculator.
How to Raise Total Alkalinity in a Pool
Low alkalinity makes pH bounce around and water corrosive. How to raise total alkalinity with baking soda, how much to add and how it differs from raising pH.
Key takeaways
- Keep total alkalinity at 80–120 ppm so pH stays stable.
- Raise alkalinity with sodium bicarbonate (baking soda), added in stages.
- Baking soda raises alkalinity a lot and pH a little; soda ash raises pH much more.
On this page
Total alkalinity is the quiet workhorse of pool chemistry. It buffers pH, soaking up the acids and bases that would otherwise send it swinging. When alkalinity is low, pH becomes unstable, water turns corrosive and your chlorine becomes harder to manage.
What is total alkalinity?
Total alkalinity measures how much alkaline material, mainly bicarbonates, is dissolved in the water. Think of it as pH’s shock absorber. The recommended range for most pools is 80–120 ppm. Our pool chemistry chart shows it alongside the other key readings.
Signs your alkalinity is low
- pH that won’t stay put, jumping up and down between tests
- Etching or roughness on plaster surfaces
- Corrosion on ladders, rails and heater parts
- Stinging eyes and itchy skin
- Green-tinted water from corroded copper
How to raise alkalinity
The standard product is sodium bicarbonate, sold as alkalinity increaser and chemically the same as baking soda.
- Test first. Measure total alkalinity and pH, and know your pool volume.
- Calculate the dose. As a rough guide, about 1.5 lb of sodium bicarbonate raises alkalinity by around 10 ppm in 10,000 gallons. Check your product’s label.
- Add in stages. Add no more than about half the total dose at once, broadcasting it across the surface of the deep end with the pump running.
- Wait at least six hours, then retest before adding more.
- Rebalance pH once alkalinity is in range.
Alkalinity vs pH: which to fix first?
Fix alkalinity first. Because it stabilises pH, getting alkalinity right makes pH adjustments stick. If pH is still low afterwards, see how to raise pH.
| Product | Main effect | Use it when |
|---|---|---|
| Sodium bicarbonate (baking soda) | Raises alkalinity a lot, pH slightly | Alkalinity is low |
| Sodium carbonate (soda ash) | Raises pH a lot, alkalinity somewhat | pH is low but alkalinity is fine |
| Aeration | Raises pH without raising alkalinity | pH is low and alkalinity is high |
What causes low alkalinity?
Heavy rain, frequent acid additions, refilling with soft water and trichlor tablets, which are acidic, all pull alkalinity down over time.
If alkalinity is too high
High alkalinity makes pH drift upward and can cause cloudy water and scale. Lower it gradually with acid and aeration, as explained in our guide to lowering alkalinity; our pH guide covers acid safety.
Frequently asked questions
Can I use household baking soda in my pool?
Yes. Pool alkalinity increaser is sodium bicarbonate, the same compound as household baking soda, though pool products come in larger, more economical bags.
How long does it take for baking soda to raise alkalinity?
It dissolves quickly, but allow at least six hours of circulation before retesting.
Is low alkalinity dangerous to swim in?
It isn’t usually dangerous for a short time, but it can irritate eyes and skin and damage your pool over time. Correct it promptly.
Sources
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Keep reading
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