Industrial Softener Capacity Calculator

Calculates softener throughput (gallons) and regeneration interval using a 10% safety factor (Capacity × 0.90) to reduce hardness breakthrough risk. Common resin capacity presets per ft³ are provided (6/9/12/15 lb salt dose).

Inputs

Raw Water Hardness (gpg)

If you have ppm, divide by 17.1 to get gpg.

Iron (ppm Fe)

Adds 3 gpg per 1 ppm Fe to effective hardness.

Manganese (ppm Mn)

Adds 2 gpg per 1 ppm Mn to effective hardness.

Daily Water Use (gpd)

Enter total plant or process daily usage.

Tank Size (Diameter × Height)

Auto-fills resin volume. You can override below.

Resin Volume (cu ft) — override if needed

Capacity per ft³ (select salt dose curve)

Salt Dose (lb/ft³) — optional

If left blank, inferred from the preset (6/9/12/15).

Results

Notes & Method

Effective Hardness (gpg) = Hardness + 3×Fe(ppm) + 2×Mn(ppm).
Total capacity (grains) = (Capacity/ft³) × (Resin ft³).
Throughput (gal) = Total capacity (gr) ÷ Effective hardness (gpg).
Apply 10% safety factor: Capacity_gal_safe = Capacity_gal × 0.90 (e.g., 26,087 × 0.90 = 23,478).
Regeneration interval (days) = Capacity_gal_safe ÷ Daily use (gpd).
Salt per regeneration (lb) = Salt dose (lb/ft³) × Resin ft³.