Fleck 5600SXT Review: Judging the Valve and the Softener Separately
The Fleck 5600SXT is one of the best-supported softener control valves you can buy, but "Fleck 5600SXT" on a listing tells you about the valve, not the softener. Pentair makes the valve. A seller adds the resin, the mineral tank, the brine tank, the bypass and the warranty. Two "48,000-grain Fleck 5600SXT" softeners can ship with different resin grades, different brine tanks and different support. Buy the valve for its parts availability and simple programming. Choose the seller on resin grade, tank size and warranty.
This Fleck 5600SXT review splits those two questions. The valve is rated from Pentair's service manual and technical sheet. The systems are compared from what each seller's own listing says ships in the box. Nothing here comes from physical testing.
Disclosure: Hard Water Solved may earn a commission if you buy through links on this page, at no extra cost to you. It does not change which products we include or how we rank them. Read our disclaimer.
How this review was put together. Valve specifications from Pentair's Fleck 5600SXT downflow service manual and 5600SXT technical sheet. System contents from each seller's Amazon listing. Capacity is compared at a stated salt dose. Prices are not listed here because they change often. Use the buttons to see the current price on Amazon.
Fleck 5600SXT Review: The Valve on Its Own
The 5600SXT is a 3/4-inch piston valve with an electronic SXT controller. In a softener, it is almost always sold in its metered form, with a 3/4-inch turbine meter in the outlet. What Pentair's documents say about it:
| Feature | What Pentair's documents say |
|---|---|
| Regeneration modes | Four: meter immediate, meter delayed, time clock delayed, day of week |
| Reserve | Fixed gallons or a percentage "safety factor" from 0 to 50% |
| Day override | Forces a regeneration after a set number of days, or off |
| Power failure | Keeps time for at least 8 hours; settings stored in non-volatile memory |
| Mid-regeneration power cut | Saves its position and resumes when power returns |
| Operating pressure | Minimum 20 psi for regeneration; maximum 125 psi |
| Water temperature | Maximum 110°F |
| Flow, valve alone | About 19 gpm at a 1 bar (about 15 psi) drop; about 25 gpm at 1.8 bar |
| Tank fit | Injector and flow controls sized per tank diameter, 6 to 14 inches listed |
What the valve does well
Parts are everywhere. The 5600 has been in production for decades, and every specialist supplier sells its seal and spacer kits, pistons, injectors, meters and SXT boards. A seal kit is a small expense next to a new valve. That is the single biggest reason to choose it. How these parts wear and how a rebuild is done is covered in servicing a water softener control valve.
Programming is fully exposed. Capacity, hardness, reserve, day override, regeneration time and each cycle's length are all set from the front keypad. That matters, because the factory capacity setting is usually the box rating and needs lowering for an efficient salt dose. How the valve uses those numbers is explained in how a water softener control valve works.
It is a known quantity to plumbers. Fleck valves are familiar to most water treatment technicians, so you are not tied to the seller for service.
Where the valve is limited
It is a 3/4-inch valve. Pentair's sheet gives the valve alone about 19 gpm at a 15 psi drop. A full softener flows less, because the resin bed adds resistance. That is ample for most homes, but large houses with many bathrooms are better served by a larger valve such as the Fleck 7000SXT.
Some listings stretch the flow numbers. One 64,000-grain listing claims "up to 16 gpm"; others have quoted peak flows as high as 28 gpm. Pentair's sheet puts the valve alone at about 25 gpm at a 26 psi drop. Any system figure above that is not credible, and a system figure near it means a pressure drop you will notice in the shower.
The display and keypad are basic. No app, no Wi-Fi, no salt sensor. For many owners that is an advantage.
What Varies by Seller: Four Listings Compared
Here is what four Amazon listings for complete 5600SXT softeners say ships in the box. Where a listing does not state something, the table says so.
| DuraWater 48k | AFWFilters 48k | AFWFilters 48k, 10% resin | 64k "high flow" | |
|---|---|---|---|---|
| Amazon listing | Check price on Amazon | Check price on Amazon | Check price on Amazon | Check price on Amazon |
| Valve | 5600SXT metered | 5600SXT metered | 5600SXT | 5600SXT metered |
| Resin volume | 1.5 cu ft | 1.5 cu ft (AFW store) | 1.5 cu ft | 2.0 cu ft |
| Resin grade | "High capacity," grade not stated | 8% high capacity (AFW store) | 10% crosslink | Not stated |
| Mineral tank | 10 x 54 in | 10 x 54 in Pentair | 10 x 54 in | 12 x 48 in |
| Brine tank | 14 x 36 in, safety float | 15 x 34 in, safety float | 14 x 36 in, 250 lb salt | 18 x 33 in round |
| Bypass / connection | 1 in plastic bypass | Bypass with 1 in threaded yoke | Bypass, 1 in NPT | Bypass included |
| Warranty stated | 5-year valve (listing) | 5-year valve, 10-year tank (AFW standard) | 5-year valve, 10-year tank (AFW standard) | 5-year head, 10-year tank |
What the table shows:
- The resin grade is the biggest real difference, and the one most often missing. On chlorinated city water, 10% crosslink resin lasts noticeably longer. On AFWFilters' own store, the upgrade from 8% to 10% on a 48,000-grain system adds only a little to the price. If a listing does not state the grade, assume standard. The trade-off is set out in standard vs chlorine-resistant softener resin.
- Tank geometry changes the set-up. The 64,000-grain listing uses a 12-inch tank. Pentair's manual specifies a different injector for 12-inch tanks than for 10-inch ones. A reputable seller ships the valve configured for the tank. Check the injector colour against the manual if you are ever unsure.
- Brine tank size changes how often you add salt. An 18 x 33 round tank holds more salt than a 14 x 36, which matters on hard water.
- The warranty is the seller's, not Pentair's. Who honours it, and how quickly, is part of what you are buying.
Capacity at a Stated Salt Dose
Every listing names its softener by grain rating. Those ratings are the maximum-salt figure, and the usable figure is lower. At an efficient 6 lb of salt per cubic foot of resin, standard resin delivers roughly 21,000 grains per cubic foot. Applied to these systems:
| Resin volume | Sold as | At 6 lb/cu ft | At 15 lb/cu ft | Salt per regeneration at 6 lb/cu ft |
|---|---|---|---|---|
| 1.5 cu ft | 48,000 grain | about 31,500 | about 46,500 | 9 lb |
| 2.0 cu ft | 64,000 grain | about 42,000 | about 62,000 | 12 lb |
The method and the full table are in advertised vs usable softener capacity. The practical step is the same on every 5600SXT: set the controller's unit capacity to the usable figure for the salt dose you choose, not to the box number. Because the 5600SXT exposes that setting on its keypad, this takes two minutes.
Programming a 5600SXT System: The Numbers That Matter
Most sellers ship the controller pre-set. Check every one of these values against your own water, because the seller's defaults are a guess about your house. Here is a worked example for a 1.5 cu ft, 48,000-grain system serving four people on 15 gpg water, about 300 gallons and 4,500 grains of hardness a day.
| Setting (manual's display code) | What it does | Example value | Why |
|---|---|---|---|
| Regeneration type | Meter delayed is the usual home setting | Meter delayed | Regenerates at night once capacity is used |
| Unit capacity (C) | Grains the bed delivers per regeneration | 31,500 | Usable figure at 6 lb/cu ft, not the 48,000 box rating |
| Feed water hardness (H) | Your hardness, plus about 4 gpg per ppm of iron | 15 | From your water test |
| Reserve (RC or SF) | Soft water held back for the last day | 300 gallons, or about 20% | One day of use; the manual caps it at half the system capacity |
| Day override (DO) | Forces a regeneration after this many days | Set, not off | So a lightly used softener still regenerates |
| Regeneration time (RT) | When delayed regenerations start | 2:00 a.m. | When no one is using water |
| Brine refill time (BF) | Sets the salt dose | Depends on the brine refill control | See below |
The controller works out the gallons between regenerations from capacity divided by hardness, then subtracts the reserve. With the example values, that is 2,100 gallons of capacity and about 1,800 gallons before a regeneration is triggered, roughly six days for this household.
Salt dose comes from the refill time. The 5600SXT measures salt by how long it refills the brine tank. Pentair's manual rates its 0.25 gpm brine refill control at 0.75 lb of salt per minute. If your valve has that control, 9 lb of salt (6 lb per cubic foot on 1.5 cu ft) needs a 12-minute refill. A 0.50 gpm control delivers 1.5 lb per minute, so the same dose takes 6 minutes. Ask the seller which control is fitted, and set the refill time and capacity to match each other.
Get these two numbers to agree and the 5600SXT runs efficiently. Leave the capacity at the box rating with an efficient refill, and it will run out of soft water before it regenerates. The reasoning behind the reserve setting is in how to set softener capacity and reserve.
Valve-Only Option: Replacing an Old Head
If you already have a working tank and resin, the head can be bought alone.
Fleck 5600SXT metered replacement softener valve. The listing describes a digital, metered, on-demand softener head with a turbine meter and cable, a five-year manufacturer warranty, and notes that a yoke or bypass is sold separately.
Before replacing a head, consider a rebuild. If the old valve is a 5600 and the problem is leaking to drain, a failure to draw brine, or a stuck cycle, a seal and spacer kit or a new injector usually fixes it for much less. A new head also needs the right injector and drain flow control for your tank diameter.
Choosing a 5600SXT System for Your Water
| Your water | Pick |
|---|---|
| City water, chlorinated | 1.5 cu ft with 10% crosslink resin (like the AFWFilters 48k 10% resin system) |
| City water, chloramine | 10% resin at minimum; consider a carbon stage ahead |
| Well water, hardness only | Standard 1.5 or 2.0 cu ft system |
| Well water with low dissolved iron | A fine-mesh resin version of the same valve; standard resin is not the right choice |
| Large household, very hard water | 2.0 cu ft with an 18 x 33 brine tank; check flow needs against the 3/4-inch valve |
For the wider question of whether salt-based softening is right for you at all, see salt-based vs salt-free water treatment.
Who Should Not Buy a Fleck 5600SXT Softener
- Very large homes with high simultaneous demand. A 3/4-inch valve is the bottleneck. Look at a larger valve.
- Anyone who wants app control, salt monitoring or alerts. The SXT controller has none of these.
- Buyers who will not check the listing details. If you buy on the valve name alone, you may get standard resin on chlorinated water or an undersized brine tank.
- Wells with significant iron, manganese or sulfur. The valve is fine, but a softener alone is not the answer. Treat those first.
- Anyone who will not reprogram the capacity. Left at the box rating with an efficient salt dose, any 5600SXT system can run out of soft water before it regenerates.
The verdict of this Fleck 5600SXT review: the valve is the safe choice, cheap to maintain and serviceable by almost anyone. The softener is only as good as the resin, tank and warranty the seller pairs with it, so compare those, set the capacity honestly, and the 5600SXT will do its job for a long time.
Frequently Asked Questions
Is the Fleck 5600SXT a good water softener?
The Fleck 5600SXT is a good control valve: metered, simple to program, and so widely used that seals, pistons and circuit boards are easy to find. Whether the softener built around it is good depends on the seller, because the resin grade and volume, tank size, brine tank, bypass and warranty all vary between listings. Judge the whole package, not the valve name.
Who makes the Fleck 5600SXT?
Fleck is a Pentair brand. Pentair makes the 5600SXT control valve and publishes its manual and specification sheet. Complete softeners sold as Fleck 5600SXT systems are assembled by dealers and online sellers such as AFWFilters and DuraWater, who add their own mineral tank, resin, brine tank and bypass, and set their own warranty terms.
How many gallons per minute can a Fleck 5600SXT handle?
Pentair's technical sheet rates the valve alone at about 4.4 cubic metres per hour, roughly 19 gpm, at a 1 bar (about 15 psi) pressure drop, and about 5.8 cubic metres per hour, roughly 25 gpm, at 1.8 bar. A complete softener flows less than the valve alone, because the resin bed adds its own pressure drop. Treat any listing claiming peak flow above about 25 gpm with caution.
How long does a Fleck 5600SXT valve last?
Pentair does not publish a design life for the valve. The parts that wear, the piston, seals and spacers, are inexpensive and widely sold, and replacing them restores the valve, so its life depends more on service than on age. Seller warranties on the valve are typically five years, with tanks often covered for ten.
Should I buy 10% crosslink resin with a Fleck 5600SXT?
If you are on chlorinated or chloraminated city water, yes. 10% crosslink resin resists chlorine damage noticeably longer than standard 8% resin, and on AFWFilters' store the upgrade adds only a little to the price of a 48,000-grain system. On a well with no chlorine, standard resin is fine, and fine-mesh resin is the better upgrade if there is dissolved iron.
Can I buy just the Fleck 5600SXT head to replace an old valve?
Yes. Metered softener heads are sold on their own at specialist retailers and on Amazon. You also need a bypass or yoke, and the injector and drain flow control must match your tank diameter, which Pentair's manual lists by tank size. If the old valve is a Fleck 5600, a seal and spacer kit may fix it for much less than a new head.
