Pool Alkalinity Calculator (Baking Soda Dose)

Direction is sign-driven: gap = target − current. A positive gap raises (baking soda); a negative gap lowers (acid); zero is in range. The target is just the number you set — the dose is computed to your target, not snapped to the nearest band edge.

Raise (baking soda):
  lb = (volume_gal × Δppm) / 10,000 × 0.15      # 0.15 = 1.5 lb / 10 ppm
  e.g. (15,000 × 30) / 10,000 × 0.15 = 45 × 0.15 = 6.75 lb

Lower (muriatic acid 31.45%) — shown as a RANGE:
  low  fl oz = (volume_gal × Δppm) / 10,000 × 0.8    # PoolFormula 8 fl oz/10k/10 ppm
  high fl oz = (volume_gal × Δppm) / 10,000 × 2.6    # The Pool Nerd ~26 fl oz/10k/10 ppm
  strength scale = 31.45 / your acid % (applied to both ends)

Why a single point for soda but a range for acid: the baking-soda raise rate is consistent across sources, so it shows as one estimate. The published muriatic-acid rate diverges materially (8 vs ~26 fl oz per 10,000 gal per 10 ppm), so the lower dose is an honest band with the conservative low end as the headline — under-dose and re-test is the safe direction with a corrosive.

Strength matters: the published acid rates assume 31.45% acid. A 14.5% home-store jug needs about ×2.17 as much; we scale both band ends and flag it. Dry acid (sodium bisulfate) has no reliably-published precise TA rate across the sources we cite, so it shows as a labeled approximate band — confirm the rate on the product bag.

Baking soda vs soda ash: baking soda (sodium bicarbonate) raises total alkalinity with little pH change; soda ash (sodium carbonate) raises both pH and TA. This tool doses baking soda only.

Alkalinity is the buffer everything else leans on. The acid side of the correction, including the pH drop that rides along with it, is dosed on the muriatic acid dose calculator, and whether the resulting balance protects or attacks the surface is settled by the saturation index calculator. Operators who are tired of chasing pH every week often add borates as a second buffer instead, which the borate dose calculator sizes, and the target bands this page aims at are collected on the pool chemistry target chart.

Sources: PoolFormula — Pool Alkalinity Calculator (baking-soda raise + 8 fl oz/10k/10 ppm acid low); The Pool Nerd — alkalinity table (1.5 lb/10k/10 ppm raise + ~26 fl oz/10k/10 ppm acid high; ideal bands chlorine 80–120, saltwater 80–100).