poolchemistrycalc

Raise total alkalinity

Into 21,100 gal of water, add

11.80lb 5.35kg

HASA Alkalinity Up — sodium bicarbonate, 100.0%. Total alkalinity from 60 ppm to 100 ppm.

Total alkalinity on one scale: the band 60–180, the ideal band 80–120, the reading now at 60 ppm, and an arrow to 100 ppm carrying 11.80 lb. reads now 60 ppm target 100 ppm ideal code 60 80 120 180 11.80 lb +40 ppm with HASA Alkalinity Up

Your pool

feet, the long side
feet
inches of water, not wall height
inches of water
what your kit reads
where you want it

The answer, the drawings, every reading and every table on this page are worked for the values in these fields, and worked again as you type. The questions further down are answered for the example this page was published with.

At 21,100 gal

Every product that does this

Every product with a fetched strength that moves this reading by 40 ppm. A row we can compute a quantity for comes first.
Product Add Also moves
HASA Alkalinity Up
sodium bicarbonate 100.0% 		11.80 lb
5.35 kg		 nothing else measured

The manufacturer's own dose sentence reads: 1.5 lbs per 10,000 gallons for approximately a 10 ppm alkalinity increase. The figures above are computed from the product's strength.

In steps, if you would rather

One dose split five ways. Add a step, run the pump, and test again before the next.
To reach Add Total added
68 ppm 2.36 lb 2.36 lb
76 ppm 2.36 lb 4.72 lb
84 ppm 2.36 lb 7.08 lb
92 ppm 2.36 lb 9.44 lb
100 ppm 2.36 lb 11.80 lb

Where the band comes from

Source Range
COMAR 10.17.01.45 A(2)
conventional pool 		60–180 ppm
COMAR 10.17.01.45 A(2)
spa or hot tub 		60–180 ppm

Pool and spa rules are adopted and amended state by state, and most of the ranges here are written for public pools. Confirm every figure against the code your jurisdiction has adopted and against your own product label.

What people ask

How much baking soda raises alkalinity by 40 ppm?
11.80 lb of sodium bicarbonate in 21,100 gal, which is 5 kg. HASA's own sentence on the Alkalinity Up page reads 1.5 lbs per 10,000 gallons for approximately a 10 ppm alkalinity increase; the figure here is computed from the product's strength instead.
Should you raise alkalinity or pH first?
Alkalinity, then pH. Alkalinity buffers pH, so a pH you set before the alkalinity moves again as soon as you add the bicarbonate. Add one thing at a time and test again before the next.
What happens when pool alkalinity is low?
COMAR 10.17.01.45 sets the band at 60–180 ppm and the manufacturer's ideal band is 80–120 ppm, so a reading of 60 ppm is at or under the bottom of both. This page states those ranges and the quantity that moves the reading; it makes no claim about what the water does to a person or a surface.

Other adjustments

Updated September 2026

Sources and dates

Ranges are quoted from the code named beside them, product strengths from the manufacturer's own product page, each retrieved on the date shown.