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1. Hard water getting through — not softening
Work through these in order. The first two causes account for 80% of soft water failures.
A. Salt bridge — check this first
A salt bridge is a hardened salt crust that forms above the water level, creating an empty void below. The system goes through regeneration but draws plain water instead of brine — so the resin never recharges. The tank looks full of salt but none is dissolving.
- Open the brine tank lid and push a broom handle straight down through the salt
- If you hit a solid crust with a hollow space underneath — that's a bridge
- Pour 1–2 gallons of hot water around the edges to soften the crust
- Break up the bridge with the broom handle until salt falls to the water level
- Wait 2 hours for brine to form, then force a manual regeneration (hold Regen button ~3 sec)
Prevention: Fill tank fully, let it deplete before refilling — never top off a partially depleted tank. Topping off creates layers that cake and bridge. Pellet salt bridges less than granules in humid installations.
B. Hardness setting too low (most common programming error)
If the programmed hardness is lower than your actual water hardness, the resin exhausts before the next regeneration and hard water breaks through. This is especially common on well water where iron adds to the effective hardness load.
- Get a current water hardness test (test strips work for a quick check)
- Enter programming mode (hold both up/down arrows 3 sec) and navigate to the H setting
- For city water: set H to your tested GPG value
- For well water with iron: add 4 GPG per PPM of iron to the tested hardness, plus 5 GPG buffer (see Section 7)
C. Clogged brine injector
The brine injector (also called the injector nozzle or venturi) draws brine from the tank into the resin. Scale, iron deposits, or debris can clog the tiny orifice — the system regenerates but uses plain water instead of brine.
- Locate the injector cap on the side of the control head (usually a plug with a small cap)
- Remove the cap (no tools needed — it unscrews or pops off)
- Pull out the injector nozzle and the injector screen below it
- Soak both in white vinegar for 30–60 minutes
- Use a thin wire or toothpick to clear the nozzle orifice — hold it to light to verify it's clear
- Rinse and reinstall. Force a manual regeneration and test water hardness after
Replacement injector kits are available on Amazon for $8–$15 — order a spare if you're on well water with iron, as partial clogging can recur.
D. Bypass valve in bypass position
Check the bypass valve at the back of the control head. On the 3-valve bypass (separate inlet/outlet valves), both valves should be open and the center bypass closed. On the integrated bypass, the handle tab should point toward the control head (service position), not away from it (bypass).
This is easy to accidentally trigger during plumbing work or when someone unfamiliar with the system touches the valves.
E. Iron-fouled resin
Iron gradually coats the resin beads, blocking ion exchange sites. The softener regenerates normally but delivers partially hard water because the resin capacity is reduced. Most common on well water without an upstream iron filter.
Treatment: pour 16 oz of resin cleaner (Res-Up, Morton MWSC, or EcoPure EPCL) into the brine well tube — not onto the salt — then force a regeneration. Repeat monthly (or every two weeks for well water with iron above 1 PPM).
If resin cleaner doesn't restore softening after 3–4 cycles, the resin may need replacement. Resin for a 1.5 cu/ft tank costs $60–$120 — a DIY replacement if you're comfortable draining and repacking the tank.
F. Meter not counting (turbine fouled)
On metered units: watch the gallon display while running a tap. The number should count down. If it's not moving, the turbine paddle in the meter may be coated with iron, scale, or debris — the system thinks no water is being used and never triggers regeneration.
- Put the softener in bypass
- Remove the meter from the side of the control head (two screws)
- Clean the paddle wheel with vinegar; rinse and reinstall
- Replacement meter units are $25–$45 if cleaning doesn't restore function
2. Not regenerating automatically
Check power and time display
The 5600SXT display must show a time of day (not just the gallon count) for time-based regeneration to trigger. If the display shows dashes or a static number after a power outage, the clock has been lost. Enter programming mode and reset the current time.
Verify day override (DO) and meter settings
On metered units: if the turbine isn't counting (see Problem 1F), the gallon trigger never fires. On time-clock units: check the Day Override (DO) setting in programming. If set to 14, the system only regenerates every 14 days regardless of usage.
Recommended settings: Day Override 7 (weekly minimum), Regen Time 2:00 AM. For well water: Day Override 3–5 depending on iron load.
Force a manual regeneration to confirm the mechanism works
- Press and hold the Regen button (circular button on the face) for approximately 3 seconds
- The display should change to show a backwash countdown or BW
- You should hear water flowing to the drain within 30 seconds
- If nothing happens, check that the motor cable is connected at the back of the control head
3. Water running continuously to drain
Water running to drain during service (not during regeneration) means the valve is stuck in a regeneration position or there's a bypass leak around the piston.
Step 1: Try advancing the valve cycle
Press the Regen button to advance the valve to the next cycle position. Sometimes the valve stops mid-cycle during a power outage and gets stuck. Pressing Regen multiple times may walk it back to the service position.
Also try: unplug the unit for 60 seconds, plug back in. The motor may attempt to self-home to the service position on restart.
Step 2: Piston, spacer, and seal kit ($15–$30)
If the valve advances normally but drain flow continues during service, the piston seals are worn and water is bypassing past the brine draw port into the drain. The piston and spacer kit is the standard repair:
- Put the system in bypass and relieve pressure
- Remove the drive cap assembly (one screw at the top of the control head)
- Pull out the piston assembly — it slides out with the drive cap
- Inspect spacers and seals for wear, cracking, or deformation
- Replace the full kit; lubricate new seals with silicone grease before installing
- Reinstall and restore water slowly. Test for drain flow in service position
4. Brine tank full or overflowing with water
The brine tank should have 6–12 inches of water at the bottom in normal operation — enough to dissolve salt into brine between regenerations. A completely full or overflowing tank means the refill control isn't shutting off properly.
Check the brine tank float assembly
Inside the brine well tube (the small white tube inside the salt tank), there's a float assembly with a safety shutoff. If the float is stuck in the down position (valve open), water will continue to fill indefinitely.
- Remove the brine well cap and pull out the float assembly
- The float should slide freely up and down the tube — if it's stiff or stuck, clean with warm water
- Check the small air check valve at the bottom of the float — it should seal when the float rises
- Replacement float assemblies are $15–$25 if cleaning doesn't restore function
Check the drain line flow control (DLFC)
A clogged DLFC button (the small disc inside the drain fitting) reduces drain flow below the rate needed to pull brine out of the tank during the brine draw cycle. Brine isn't drawn out, so refill water adds on top — the tank fills over time.
Remove the drain line elbow from the control head, pop out the DLFC button, and soak in vinegar. DLFC buttons are less than $5 to replace.
Check brine fill time (BF) programming setting
In programming mode, navigate to BF (Brine Fill). Standard setting is 6–12 minutes. If someone set it to 60, the tank will overfill on every regeneration. Normal BF for a 1.5 cu/ft tank is approximately 8–10 minutes.
5. Regenerating too frequently — using too much salt
Hardness set too high
If the programmed hardness is much higher than your actual water hardness, the calculated capacity per regeneration is much lower than the actual capacity — triggering regeneration far more often than needed. Retest your water and verify the setting matches.
Iron reducing effective resin capacity
Iron fouling reduces the number of active exchange sites on the resin. The system compensates by regenerating more often to try to keep up with hardness demand. Clean the resin with a resin cleaner and verify iron is being filtered upstream before the softener.
Household water use has increased
On metered units, a new appliance, extra occupants, or a leak (running toilet, dripping faucet) triggers earlier regeneration because the gallon counter hits the threshold faster. Check for leaks first — a toilet valve leak can consume hundreds of gallons per day invisibly.
Resin channeling
In rare cases, water finds a direct path through a void in the resin bed (channeling), bypassing most of the resin. Symptoms: very frequent regeneration despite normal water use, and hardness that isn't fully removed despite regenerating. The resin bed needs to be backwashed aggressively or repacked.
6. Error codes
After clearing an error code by power cycling, the code will not return if the underlying issue is resolved. If Err 1 or 2 returns immediately after power cycling, the motor or drive cap assembly needs replacement — both are available on Amazon for $20–$40 and are straightforward DIY repairs.
7. Well water with iron — special considerations
The 5600SXT wasn't designed specifically for iron-rich well water, but it handles it well if set up correctly. Two things matter above all: iron compensation in the hardness setting, and biweekly resin cleaning.
For every 1 PPM of iron, add 4 GPG to your programmed hardness
Example: Your water tests at 18 GPG hardness and 2 PPM iron.
Iron compensation: 2 × 4 = 8 GPG. Add 5 GPG seasonal buffer. Programmed hardness = 18 + 8 + 5 = 31 GPG — even though tested hardness is only 18. Without this, the resin exhausts much faster than the meter expects and hard water breaks through.
Use resin cleaner every two weeks — not monthly
On city water, monthly resin cleaning is adequate. On well water with iron, biweekly is the standard from US Water Systems, Kinetico, and most well water technicians. Pour 16 oz of resin cleaner (Res-Up, Morton MWSC, EcoPure) into the brine well tube — not onto the salt — before a regeneration. See our resin cleaner guide for the best products for well water.
Install an iron filter upstream if iron exceeds 3 PPM
The 5600SXT resin can handle low levels of clear-water iron with proper iron compensation and regular cleaning. Above 3 PPM, a dedicated iron filter (air injection oxidation, like the Springwell WF1) installed upstream is the right answer — it removes iron before it reaches the resin, protecting the resin bed and extending its life significantly. See our water softener for iron-rich well water guide.
Use high-purity solar salt or pellets — not rock salt
Rock salt has higher insoluble content than solar salt or evaporated pellets. On well water that's already challenging, the extra impurities from rock salt accumulate in the brine tank faster and contribute to injector clogging. Use 99.6%+ purity solar granules or pellets. See our salt guide for well water.
8. After a power outage
The 5600SXT has no battery backup. Every power outage resets the clock to 12:00 and loses the current day/gallon count. The hardness setting and all programming parameters are retained in non-volatile memory — those don't need to be re-entered.
Reset the time of day
Hold the up or down arrow until the display starts flashing. Set the correct current time, then press Set (or wait 5 seconds) to lock it in. The system will now regenerate at the programmed Regen Time (RT) relative to the correct clock.
Force a manual regeneration if uncertain
If you don't know when the last regeneration occurred before the outage, force one manually. Better to regenerate once unnecessarily than to let resin exhaust and deliver hard water.
Frequent power outages? Consider an upgrade
If you're in a rural area with regular grid interruptions, the repeated clock resets become genuinely inconvenient. The US Water Systems MatriXX softener includes a 9V battery backup that maintains the clock through outages. See our FleXX vs MatriXX comparison for the full breakdown.
Common replacement parts and what they cost
All parts are available on Amazon — search "Fleck 5600SXT [part name]". AFWFilters and Water Right Group also stock genuine Fleck parts if Amazon doesn't have the exact item. The 5600SXT's aftermarket parts ecosystem is one of its strongest features — parts are widely available and the repair cost to keep a working unit running is low.
Common questions
How do I force a manual regeneration on the 5600SXT?
Press and hold the circular Regen button for approximately 3 seconds. The display should change to show BW (backwash) or a countdown. You should hear water flow to the drain within 30 seconds. The full regeneration cycle takes 90–120 minutes — do not interrupt it.
My 5600SXT is regenerating but water is still hard — what's wrong?
Most likely: the brine injector is clogged (resin regenerating with plain water instead of brine), or the hardness setting is too low for your actual water chemistry. Clean the injector first — it's the quickest fix and requires no parts. Then verify your programmed hardness includes iron compensation if you're on well water.
How long does Fleck 5600SXT resin last?
Typically 15–20 years on city water with proper maintenance. On well water with iron, resin life is shorter — 8–12 years is more realistic without an upstream iron filter. Signs of resin exhaustion: softener regenerates normally, salt is drawing properly, injector is clean, but hardness still isn't fully removed after multiple cycles. A resin cleaner treatment is worth trying first before replacing the resin.
Can I use any brand of salt in my Fleck 5600SXT?
Any high-purity water softener salt (solar granules or evaporated pellets, 99.6%+ pure) works in the 5600SXT. Avoid rock salt — it has higher insoluble content that accumulates in the brine tank and can clog the injector. For well water with iron, pellets are preferred over granules because they're less prone to bridging in humid installations.
