Baking soda vs soda ash for pool alkalinity: Baking soda raises alkalinity without spiking pH

Baking soda (sodium bicarbonate) is the go-to for raising total alkalinity without sending pH through the roof. Soda ash (sodium carbonate) raises both alkalinity and pH significantly — good if you need both, bad if you only need alkalinity. Typical dose is about 1.5 lbs per 10,000 gallons for a 10 ppm alkalinity bump.