Set Your Water Softener From Tested Hardness—not Factory Defaults

Set the hardness control to the hardness of the water entering the softener, in the units your controller requires. Match any programmable grain capacity to the capacity available at the actual salt dose—not simply the advertised grain rating. Then check the clock, regeneration start time, reserve and day override.

There is no universal set of water softener settings. Before changing anything, photograph the existing screens and identify the complete system model, control valve and matching manual. A valve name alone may not identify the resin quantity or salt-dose specification. The Fleck 5600SXT job specification sheet, for example, separately records capacity, tank size, salt setting, injector and flow controls.

What each setting means

These are common functions, not universal screen names. Some systems calculate capacity or reserve automatically; others expose them as separate settings.

Setting	What to enter or check	Important distinction
Hardness, often H	Tested inlet hardness, converted to the required units, plus any model-required compensation	It is not a desired outlet-hardness setting
Present time or clock	Correct local time, including AM/PM	A wrong clock shifts scheduled regeneration
Recharge/regeneration time, often RT	A start time when little or no treated water is needed	Start time is not regeneration frequency
Grain capacity, often C	System capacity at the selected salt dose	The maximum advertised rating may require much more salt
Reserve, often RC or SF	The model-specified volume or percentage held back until regeneration	Gallons and percentages are different inputs
Day override, often DO	The maximum interval specified for your system and water conditions	On a metered unit, it can trigger regeneration even with capacity remaining
Salt level	Actual salt height on the tank’s numbered scale, where fitted	A refill reminder is not the salt dose per regeneration

The control and reserve definitions above are illustrated in the Pentair Fleck manual. GE’s GXSH40V/GXSH45V manual, pages 16–19, distinguishes clock, hardness, recharge time and salt-level inputs.

1. Enter the correct hardness number

Use an untreated cold-water sample entering the softener, not the softened outlet. If you need a testing procedure, see how to measure water hardness at home.

For a controller using grains per U.S. gallon:

Hardness in GPG = total hardness in mg/L as CaCO₃ ÷ 17.1

For example, 342 mg/L ÷ 17.1 = 20 GPG. Entering 342 into a GPG control would be a unit error. GE provides this conversion in its hardness-programming instructions. Use total hardness—not TDS or a calcium-only result—and follow your manual’s rounding instructions.

Iron compensation is model-specific

Do not add an arbitrary hardness allowance for every well. First establish what iron reaches the softener and whether the system is suitable for treating it.

For example, GE instructs owners of the GXSH40V/GXSH45V to add 5 GPG for each 1 ppm of ferrous, clear-water iron. With 20 GPG hardness and 2 ppm of that iron entering the unit, the compensated setting is 30. The same manual says these systems do not remove ferric or bacterial iron. That adjustment is therefore not a treatment solution for every kind of iron, or a universal rule for other brands. Source: GE manual, pages 6 and 17.

2. Match grain capacity and salt dose

Lowering the salt dose also lowers the capacity restored at regeneration. Leaving a high capacity setting unchanged can make the controller expect more softened water than the resin can deliver. Madison Metropolitan Sewerage District’s softener training workbook explains this relationship: lower doses generally provide better salt efficiency, but require more regenerations for the same hardness load.

A concrete example: GE’s April 2026 manual lists these GXSH40V rated capacity/dose pairs, tested with pellet-grade sodium chloride:

• 11,700 grains at 2.3 lb of salt
• 31,500 grains at 8.7 lb
• 40,000 grains at 15.1 lb

Thus, “40,000 grains” and the lowest salt dose are not simultaneous operating specifications. The manual also states that its published efficiency rating applies only at the lowest listed dose. These are model-specific performance data, not settings to copy into another system. Source: GE specifications, page 3.

On systems with programmable brine-fill minutes, obtain the matching capacity and fill setting from the system supplier. Do not copy minutes from another unit: the Fleck specification sheet separately identifies the brine-line flow control, which determines refill flow. Pentair also advises consulting a professional before entering master programming. Source: Fleck service manual.

3. Check regeneration timing and reserve

A metered delayed-regeneration controller tracks water use and waits until its programmed start time to regenerate. Reserve must cover consumption between reaching the regeneration threshold and that start time. A timer-controlled unit instead regenerates on a scheduled interval. On the Fleck controller, day override is a maximum interval for metered operation but determines frequency in time-clock operation. Source: Pentair timer-operation instructions.

For a fixed-reserve metered controller using grains and U.S. gallons, the basic calculation is:

Gallons before reserve = operating grain capacity ÷ programmed hardness in GPG

Gallons available before the trigger = that result − reserve gallons

As an illustration—not a programming recommendation—24,000 grains at 20 GPG gives 1,200 gallons. Subtracting a 200-gallon reserve leaves a 1,000-gallon trigger allowance. If softened-water use is 250 gallons/day, that allowance represents about four days. The Fleck manual documents the capacity/hardness/reserve calculation.

Choose a low-use regeneration window. GE’s default is 2:00 a.m., with approximately two hours required; its listed models supply hard water to the house during recharge. Shift that window if your household showers or runs appliances then. Recheck the clock after a long power outage. Source: GE programming and memory instructions.

Verify the change with water tests

After a complete regeneration, compare untreated and treated cold-water hardness. Test the treated water again near the expected end of the service run; a good result immediately after regeneration does not establish that capacity lasts until the next cycle. Keep a short record of hardness, water use, regeneration dates and salt additions.

If hard water persists, do not keep raising hardness or shortening rinse cycles to compensate. Check salt availability, bypass position and error messages using the water softener troubleshooting guide. Correct settings cannot substitute for a functioning brine system or serviceable resin.