Quick Reference
- Chemical name: sodium bicarbonate (NaHCO3), sold as Alkalinity Increaser
- Raises: total alkalinity strongly, pH slightly
- Typical target TA: roughly 70-90 ppm for many pools; 60-80 ppm is common for saltwater
- Rule of thumb: about 1.4 lb per 10,000 gallons raises TA around 10 ppm
- Same as: grocery store baking soda, if the label says 100% sodium bicarbonate
Table of Contents
What It Does
Baking soda raises total alkalinity. It nudges pH up a little, but not much, and that is precisely why it exists as a separate product from soda ash.
Total alkalinity is your buffer. It is what keeps a small chemical addition from swinging pH across the whole scale. Low TA means less buffering capacity, so pH gets twitchy and hard to hold. That is the problem baking soda solves. It is not a pH product, and reaching for it when pH is your actual complaint will leave you with high alkalinity and the original problem.
When You Actually Need It
- TA down around 60 ppm or below, especially if pH will not hold still.
- After a heavy acid treatment that pulled TA lower than you meant to.
- Fresh fill water that came in with low alkalinity, which is common in some regions.
On plaster pools: ignore anyone who gives you a single TA number for plaster. What matters is the overall saturation balance, TA together with calcium hardness, pH, and temperature. Many plaster pools sit fine around 70-90 ppm, but the right number depends on the rest of your water.
When You Do Not
Most pools do not need baking soda on any kind of schedule. If you are adding it weekly, something is eating your alkalinity, and it is usually acid you are adding to fight a persistent pH rise. Adding base and acid in a loop is a common, expensive habit that gets you nowhere.
High TA is its own problem. It makes pH stubborn to move and increases the tendency for pH to drift upward in an aerated pool. Getting it back down means muriatic acid plus aeration, which is a slower chore than raising it was. Do not overshoot.
Dosing
About 1.4 lb per 10,000 gallons raises TA roughly 10 ppm. Treat that as a rule of thumb and use a calculator when precision matters.
- Pump running.
- Broadcast slowly across the pool, or pre-dissolve in a bucket first.
- For a large correction, split it into a few smaller doses rather than one big one. Better control, less chance of clouding, and you can stop when you hit your number.
- Circulate at least 2-6 hours before retesting. If the reading surprises you, check again the next day once it has fully mixed.
- Store it sealed and dry. Do not mix dry chemicals together.
Grocery Store vs. Pool Store
It is the same chemical. Pool store Alkalinity Increaser and a box of Arm and Hammer are both sodium bicarbonate, and the pool store version is frequently several times the price per pound.
Buy whichever is cheaper per pound, usually a bulk bag from a warehouse club. Two things to check first: confirm the label says 100% sodium bicarbonate with no additives, and confirm the pool product you are comparing against is not a blend, because some are.
Saltwater Pools
Saltwater chlorine generators tend to drive pH upward, mostly through carbon dioxide outgassing at the cell and the returns. Running TA toward the lower end, around 60-80 ppm, gives less carbonate available to outgas and takes some of the push out of that pH climb.
Do not chase 100+ ppm TA in a saltwater pool because a generic chart told you to. You will just be adding acid more often.
Spas
Spas burn through alkalinity quickly thanks to constant aeration and tiny water volume. Small, frequent doses beat one large correction, and you will be testing more often than you would on a pool.
Trouble Free Pool is the best free resource for working through alkalinity and pH together rather than one at a time.