Baking Soda vs Soda Ash
They look almost identical in the bucket and they are chemical cousins, but they do two different jobs. Baking soda (sodium bicarbonate) is your total alkalinity fix — it barely touches pH. Soda ash (sodium carbonate) is a pH increaser that lifts pH fast and only nudges alkalinity. Add the wrong one and you either overshoot pH or chase an alkalinity number that will not move. The rule most pool owners never get told: read your test kit first, then pick the powder.
Side by side
| Baking Soda | Soda Ash | |
|---|---|---|
| Chemical name | Sodium bicarbonate (bicarb) | Sodium carbonate |
| Also sold as | Alkalinity increaser / Alkalinity Up | pH increaser / pH Up |
| Mainly raises | Total alkalinity (TA) | pH |
| Effect on pH | Small — nudges pH up only slightly | Large — moves pH fast |
| Effect on alkalinity | Large — the reason you use it | Modest — raises TA a little too |
| Typical dose | ~1.5 lb per 10k gal ≈ +10 ppm TA | ~6 oz per 10k gal ≈ +0.1 pH (at TA ~100) |
| Overdose risk | Forgiving — hard to cause harm | Cloudy water or scaling if overdosed |
| Best for | Low alkalinity, pH already okay | Low pH, alkalinity already okay |
The verdict
your total alkalinity is below the 80 to 120 ppm range and pH is roughly fine. Sodium bicarbonate lifts TA without shoving pH out of range, so it is the safe, forgiving choice for the most common problem — soft, unbuffered water that lets pH bounce all over the place.
pH is low (below about 7.2) but alkalinity already sits in range. Soda ash raises pH quickly with only a small TA bump. Dose it conservatively and pre-dissolve it — a little moves pH a lot, and too much at once can cloud the water, especially if calcium hardness is high.
Pros & cons
- Fixes low alkalinity without spiking pH
- Very forgiving — overdosing rarely causes harm
- Cheap and sold everywhere as the same compound
- Barely moves pH, so it will not fix low pH on its own
- Large TA corrections need several pounds
- Wrong tool if alkalinity is already fine
- Raises low pH fast
- You use far less than baking soda
- Nudges alkalinity up a little at the same time
- Easy to overshoot pH
- Can cloud water or cause scaling if overdosed
- Should be pre-dissolved and added slowly
Fix alkalinity first, then pH. Get total alkalinity into the 80 to 120 ppm range with baking soda — stable TA acts as a buffer and stops pH from bouncing. Once TA is set, fine-tune pH with soda ash if it is low, or muriatic acid if it is high. Chasing pH before alkalinity is why so many people add powder for a week and watch nothing hold. Test, correct TA, then correct pH — in that order.
Common questions
Is alkalinity increaser the same as baking soda?
Yes. Almost every product sold as pool "alkalinity increaser" or "Alkalinity Up" is just sodium bicarbonate — the same compound as baking soda. The pool-store box and the grocery-store bag are chemically identical, which is why many owners buy plain baking soda and save the markup. Pool-grade is simply sodium bicarbonate without the trace anti-caking agents in some food brands.
Is soda ash the same as pH increaser?
Usually, yes. Most "pH increaser" or "pH Up" products are sodium carbonate, which is soda ash. It raises pH quickly and lifts total alkalinity slightly at the same time. Borax is the other common pH-up option — it raises pH with almost no effect on alkalinity, so some owners prefer it when TA is already where they want it.
Does baking soda raise pH or just alkalinity?
Baking soda mainly raises total alkalinity. It does nudge pH upward a little, but the effect is small and it will not pull a genuinely low pH back into range on its own. If pH is the real problem, soda ash or borax is the right tool; baking soda is for buffering the water by raising TA into the 80 to 120 ppm band.
Can I use soda ash to raise alkalinity?
It will raise alkalinity somewhat, but it is the wrong tool for the job. Soda ash raises pH far more than it raises TA, so using it to chase an alkalinity number will send pH sailing past the top of the range long before TA reaches target. For a TA-only correction, use baking soda; save soda ash for when pH itself is low.
How much baking soda vs soda ash do I add?
Very different amounts, because they do different jobs. Roughly 1.5 lb of baking soda per 10,000 gallons raises total alkalinity about 10 ppm. Soda ash is far more concentrated for pH — around 6 oz per 10,000 gallons lifts pH about 0.1 at a typical alkalinity. Add in small doses, let the water circulate, and retest before adding more. Our alkalinity and pH calculators do the exact math for your pool size.
Will baking soda raise pH in an above ground pool?
Only slightly, and the pool being above ground or in-ground makes no difference — the chemistry is the same. In any pool, baking soda raises total alkalinity and moves pH just a little. If your above ground pool has low pH specifically, reach for soda ash; if the water is unbuffered and pH keeps drifting, baking soda to raise TA is what steadies it.