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Operating Case

Enter your system parameters. Results update automatically.

Total hardness of the water entering the softener.
mg/L

Total hardness in, mg/L as CaCO₃. Iron adds to it below.

Hardness UnitMilligrams per liter as CaCO₃, or grains per gallon. 1 gpg is 17.1 mg/L.
Effective hardness (with iron)171 mg/L 10.0 gpg
Dissolved iron loads the resin like extra hardness. Each 1 ppm Fe is treated as about 4 gpg of additional hardness.
ppm

ppm Fe, 0 to 10.

Average daily softened water demand. If this softener feeds a boiler, use the makeup rate from the Boiler Blowdown Calculator.
gal/day

Softened demand. Boiler makeup if it feeds a boiler.

Total softening resin in the vessel (per tank for twin units). Nameplate or spec sheet.
ft³

Per tank for twin units.

Water sent to drain during backwash, brine draw, and rinse, per cubic foot of resin at each regeneration.
gal/ft³

gal per ft³ per regen. 30 to 150.

Pounds of salt used per cubic foot of resin at each regeneration. Higher dose, more capacity per run, lower salt efficiency.
lb/ft³

30.0 kgr per ft³ at this dose. More salt buys capacity at falling efficiency.

Capacity by Salt Dose (8% SAC resin)4 lb/ft³: 17.0 kgr/ft³6 lb/ft³: 20.0 kgr/ft³8 lb/ft³: 24.0 kgr/ft³10 lb/ft³: 27.0 kgr/ft³12 lb/ft³: 28.5 kgr/ft³15 lb/ft³: 30.0 kgr/ft³20 lb/ft³: 32.0 kgr/ft³
Portion of resin capacity held back so the softener regenerates before hardness breaks through. 10% is standard field practice.
%

Held back so the valve regenerates before hardness breaks through. 10% is standard field practice.

Click on any stream to learn more.

Softener Capacity and Regeneration

All quantities are live and update with your inputs.

Operating Conditions
Hardness
171 mg/L
Iron
0 ppm Fe
Daily Use
5,000 gal/day
Resin
3 ft³
Salt Dose
15 lb/ft³

Key Results

Primary outputs and operational context based on your inputs.

At 6 lb/ft³ this same softener would use about 6,083 lb/yr of salt and regenerate every 25.9 hours.

Days Between Regenerations Water treated per regeneration over the daily use. Around three days is a common design target.

1.6 days

225.3 regens a year

Around three days is a common design target.

Annual Salt Salt per regeneration times regenerations a year, in pounds and 40 lb bags.

10,139 lb

253 bags of 40 lb

45 lb a regeneration at 15 lb/ft³.

Gallons per Regeneration Usable capacity, after the reserve, over the effective hardness: the water one regeneration buys.

8,100 gal

81.0 kgr usable

After the 10% reserve.

Effective Hardness Hardness plus 4 gpg for every ppm of iron. The load the bed actually sees.

171 mg/L

10.0 gpg

No iron load entered.

Salt Efficiency Salt spent per thousand grains of hardness removed, with the reserve counted. Leaner dosing wins here and loses on run length.

0.556 lb/kgr

225 gal regen water

Leaner dosing wins here and loses on run length.

Salt Price Your delivered salt cost per pound. Bagged salt is typically several times the price of bulk.
$
per lb
Annual Salt Cost$1,217

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