Total alkalinity (TA) is the buffer that keeps your pH stable. Without adequate alkalinity, pH swings wildly with every chemical addition, rain event, or CO2 change — a condition called pH bounce. With proper alkalinity (80–120 ppm), pH is far more stable and easier to manage.
Low alkalinity is a root cause of many pool problems because it makes every other chemical adjustment unreliable.
The chemical for raising alkalinity is sodium bicarbonate (NaHCO₃). This is the same compound as baking soda. Pool stores sell it as "alkalinity increaser" or "total alkalinity up." It is the exact same chemical at about 5x the price. Either product works.
| Current TA (ppm) | Target TA (ppm) | Increase Needed | Dose per 10,000 gal |
|---|---|---|---|
| 40 | 100 | 60 ppm | 9 lbs |
| 60 | 100 | 40 ppm | 6 lbs |
| 70 | 100 | 30 ppm | 4.5 lbs |
| 80 | 100 | 20 ppm | 3 lbs |
For larger pools, multiply proportionally: a 20,000-gallon pool needs double these amounts.
Do not confuse sodium bicarbonate (raises alkalinity) with sodium carbonate (raises pH). Soda ash (sodium carbonate) is a much stronger pH raiser and has a more dramatic effect on pH. For alkalinity adjustment with minimal pH change, always use bicarbonate.
High alkalinity (above 150 ppm) makes pH very difficult to lower — it resists acid additions. Lower it with muriatic acid, added in front of a return jet in a specific technique: aerate the water (fountain, waterfalls, or jets) to help CO2 off-gas after adding acid. This lowers alkalinity without pushing pH down as much. It is a slower process than raising alkalinity.
Alkalinity and pH are related but different:
PoolLens logs your alkalinity readings over time and calculates the exact dose of sodium bicarbonate needed for your pool size. Stop guessing — get the precise amount every time.
Open PoolLens Free →The ideal total alkalinity is 80–120 ppm. Below 60 ppm, pH swings wildly. Above 150 ppm, pH becomes difficult to lower and scale may form. Most pros target 90–110 ppm as the sweet spot.
Low alkalinity (below 60 ppm) causes rapid, unpredictable pH swings — called pH bounce. Small chemical additions cause large pH changes, making the pool corrosive and hard to manage. Fix alkalinity first before adjusting pH.
Sodium bicarbonate raises both alkalinity and pH slightly (usually 0.1–0.2 units). Sodium carbonate (soda ash) primarily raises pH with a secondary effect on alkalinity. Use bicarbonate when you need to raise alkalinity without dramatically moving pH.
Wait 4–6 hours after adding sodium bicarbonate, then retest before adding anything else. Never add multiple chemicals simultaneously — one at a time, wait, retest, then decide on the next addition.
Yes — regular arm-and-hammer baking soda is chemically identical to pool-branded alkalinity increaser. Use the same sodium bicarbonate product at about 20% of the cost. Make sure it is pure sodium bicarbonate with no additives.