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

Baking soda (sodium bicarbonate) raises total alkalinity with minimal pH change because its pH is ~8, while soda ash (sodium carbonate, pH ~11) boosts both. Add about 1.5 lbs per 10,000 gallons to raise alkalinity by 10 ppm, then test. If pH creeps up, aeration can bring it down. Don’t overdo it — high alkalinity clouds water and locks pH.