Fleck 5600SXT Programming: Settings by Softener Size

By SubcontractorHub Editorial Team·Published September 2026

The Fleck 5600SXT shows up on more residential softeners than almost any other control valve, which means most techs have programmed one. Far fewer have programmed one correctly for the house in front of them. The valve ships with generic capacity, hardness and brine fill values, and a lot of installs leave those in place. The result is a softener that either burns salt on a schedule it does not need or runs past exhaustion and lets hard water through. This guide covers what each master setting means and, more usefully, how to work out the numbers for C, H, reserve and BF.

What the Fleck 5600SXT Is

The 5600SXT is a downflow control valve for a single softener tank, paired with the SXT digital timer. The valve body handles the flow path through each regeneration stage; the SXT timer decides when to regenerate and how long each stage runs. It can run as a time clock (regenerate every set number of days, or on set days of the week) or as a metered valve that counts gallons through a flow meter and regenerates based on actual use.

Fleck is a Pentair brand. SubcontractorHub is not affiliated with Pentair or Fleck; this is an independent guide for installers.

How to Enter Master Programming

Master programming is where the settings below live. On many SXT timers the service manual describes it like this: set the time of day to 12:01 PM, then press and hold the Up and Down buttons together for about five seconds until the first setting appears. From there you step through each setting, change values with the arrows, and the timer saves when you exit.

That entry sequence has varied between firmware and manual revisions, and so has the order and naming of the settings. Confirm it against the service manual printed for your valve (the model and revision are usually on the timer or the valve label). If a sequence you found online does not work, trust the manual for your unit over the forum post.

Fleck 5600SXT Master Programming Settings

Codes below are the ones commonly shown on the display. Not every setting appears on every firmware, and some only appear once an earlier choice unlocks them (the reserve options only matter in metered modes, for example).

Cycle times are common starting points, not universal values. Resin volume, media type and the backwash flow control fitted to the drain all change what is right.

Choosing the control type

Meter delayed suits most homes: the valve counts gallons and, once remaining capacity falls below the reserve, schedules regeneration for RT. Meter immediate regenerates the moment capacity reaches zero, which fits sites that draw water around the clock but means regenerating during use. Time clock and day of week ignore actual use entirely. They are the fallback when there is no working meter, and they will waste salt in light weeks and run short in heavy ones.

Calculating C, H, Reserve and BF

These four settings are where the defaults do the damage. The method below matches the one behind our water softener sizing calculator.

H: compensated hardness

Start with the tested hardness in grains per gallon, then add about 4 gpg for every 1 ppm of dissolved iron and 4 gpg for every 1 ppm of manganese. Iron and manganese use up exchange capacity the same way hardness does. Enter the compensated number as H. Entering the raw figure is the most common programming error there is.

C: unit capacity

Capacity depends on how hard you regenerate the resin. Approximate figures per cubic foot:

• 6 lb salt per cu ft gives about 20,000 grains (most salt-efficient)
• 10 lb salt per cu ft gives about 25,000 grains
• 15 lb salt per cu ft gives about 30,000 grains (most capacity, least efficient)

Multiply by the resin volume in the tank. On common SXT firmware C is entered in kilograins, so 30,000 grains goes in as 30. Check what the screen expects on your unit before you enter it, because entering 30000 where 30 is wanted (or the reverse) makes every metered calculation meaningless.

Reserve

In meter-delayed mode the valve waits until RT to regenerate, so it needs enough capacity left to get through the rest of the day. Size the reserve to about one day of use: daily gallons times H gives grains per day. As a percentage, that is daily grains divided by C. If your firmware takes a fixed reserve instead of a safety factor, enter it in the units it asks for and confirm on screen.

BF: brine fill time

Each gallon of fill water dissolves about 3 lb of salt. So BF in minutes is the salt dose in pounds, divided by 3, divided by the rating of the brine line flow control (BLFC) in gallons per minute. The BLFC is a small flow washer in the brine refill path and its rating is usually marked on the part; read it off the one in your valve rather than assuming. Use the water softener regeneration calculator to check how often the result will regenerate and how much salt it will use per month.

Settings by Softener Size

C and salt dose for common resin volumes, with BF shown for an example 0.5 gpm BLFC. Recalculate BF with your actual BLFC rating. C is rounded down and BF rounded to the nearest minute.

Worked Example: A Family of Four on Well Water

Four people at 75 gallons per person per day use 300 gallons a day. The water tests 15 gpg hardness with 1 ppm of iron, so H is 15 + (1 × 4) = 19 gpg. Daily load is 300 × 19 = 5,700 grains.

The unit has 1.5 cu ft of resin. Dosed at 6 lb per cu ft, it takes 1.5 × 6 = 9 lb of salt per regeneration and delivers 1.5 × 20,000 = 30,000 grains, so C = 30. That is 30,000 ÷ 5,700 = about 5.3 days of capacity.

Reserve of one day's use is 5,700 grains, which is 19% of 30,000, so a safety factor of about 20% (or a fixed reserve of about 300 gallons, if your firmware takes one) is right. In gallons, full capacity is 30,000 ÷ 19 = about 1,579 gallons; less 20% leaves about 1,263 gallons, so the valve regenerates roughly every four days in practice. DO at 7 days is a backstop that should rarely trigger. BF is 9 ÷ 3 ÷ 0.5 = 6 minutes with a 0.5 gpm BLFC. With a different BLFC, divide the 3 gallons of fill water by its rating instead (3 ÷ 0.25 = 12 minutes, for example).

When the 5600SXT Is the Wrong Valve

The 5600SXT is built for single-tank residential work. Larger resin volumes, higher peak flow, twin-tank alternating systems and light commercial jobs generally move up to a larger valve, such as a Fleck 2510SXT, a Fleck 7000 or a Clack WS1, depending on the flow and tank size. Size the job first and pick the valve second. For anything past a typical home, run the numbers through the commercial water softener sizing calculator and check the chosen valve's published flow ratings against the peak demand.

Troubleshooting After Programming

• Won't regenerate. Check CT first (a time clock set to a long DO looks like a dead valve), then that the meter is counting. If the display never moves while water runs, the meter or its cable is the problem, not the program.
• Salt not being used. Usually a BF so short it barely makes brine, an air leak at the brine line fitting, a plugged injector, or a salt bridge. Confirm the brine tank level drops during BD.
• Hardness bleed-through. Almost always H entered raw or C set too high, so the valve thinks it has more capacity left than it does. Recheck both against a fresh water test, and confirm the bypass is fully in service.

The water softener troubleshooting guide walks through each symptom in order. If you are commissioning a new unit, the programming step fits into the full sequence in how to install a water softener, and ongoing checks are covered in the water softener maintenance schedule.

For Dealers: Write the Program Down

The next tech to open that valve should not have to guess why BF is 6 or whether H was entered raw. Record the programmed settings for every install: C, H, the water test they came from, reserve, DO, RT, cycle times, BF and the BLFC rating, against the customer and the equipment serial. When the water changes or the family grows, the service call becomes a quick recalculation instead of a teardown. Keeping those records tied to the account, alongside the service schedule and salt delivery, is what water treatment contractor software is for, and it is how a single install turns into recurring service revenue. Plumbing shops that also install softeners can see the same workflow on the plumbing side.

Frequently Asked Questions

Related Guides & Tools

• Water Softener Sizing Calculator
• Water Softener Regeneration Calculator
• Commercial Water Softener Sizing Calculator
• Water Softener Troubleshooting Guide
• How to Install a Water Softener
• Water Softener Maintenance Schedule
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