How much baking soda for a 18,000 gallon pool?
To raise total alkalinity by 10 ppm in a 18,000 gallon pool, add 2 lb 8 oz of baking soda. To raise it 30 ppm, add 7 lb 9 oz. Plain grocery-store baking soda is the same chemical as any "alkalinity increaser" sold for pools.
Rule of thumb: 1.4 lb of baking soda per 10,000 gallons raises alkalinity 10 ppm, so for 18,000 gallons it's 2 lb 8 oz per 10 ppm.
Baking soda doses for 18,000 gallons
| Raise alkalinity by | Baking soda |
|---|---|
| 10 ppm | 2 lb 8 oz |
| 20 ppm | 5 lb 1 oz |
| 30 ppm | 7 lb 9 oz |
| 40 ppm | 10 lb 1 oz |
| 50 ppm | 12 lb 10 oz |
Where alkalinity should be
60 to 80 ppm with liquid chlorine or a salt cell, 80 to 120 with trichlor tablets. Low alkalinity lets pH swing; high alkalinity pushes pH up and causes scale.
It nudges pH too
Baking soda raises pH a little as well. If pH is already high, raise alkalinity in stages and let aeration settle the pH between doses.
Adding it
Broadcast it across the surface with the pump running, or pour it into the skimmer slowly. Retest after 6 hours. Big doses go in over two days.
Other pool sizes
Baking soda for a 5,000, 8,000, 10,000, 12,000, 15,000, 20,000, 25,000, 30,000 gallon pool. Not a round number? Use the baking soda calculator with your exact volume, or find it with the volume calculator.
Other chemicals for 18,000 gallons
How much shock for a 18,000 gallon pool, How much chlorine for a 18,000 gallon pool, How much salt for a 18,000 gallon pool.