Fleck 5600SXT Review: Specs, Sizing and Programming
Verdict: The Fleck 5600SXT is a proven, widely used control valve, not a complete softener. Pentair rates it for 20 gpm continuous flow, metered (demand) regeneration and tanks up to 12 inches in diameter. A Fleck 5600SXT system is a good choice for handy homeowners who want a standard, serviceable softener at a reasonable price. But the tank, resin, warranty and support all depend on the seller, and the valve does not carry NSF/ANSI 44 certification on its own, so choose the seller carefully.
What the Fleck 5600SXT Is
Fleck is Pentair's control valve brand, and the 5600SXT is its digital, metered version of the long-running 5600 valve. The valve is the "brain" on top of a softener: it measures water use, decides when to regenerate, and runs the backwash, brine draw and rinse cycles. Dealers and online sellers buy the valve and mount it on their own resin tank and brine tank, then sell the package as a "Fleck 5600SXT water softener."
That is the most important thing to understand before buying. Two "Fleck 5600SXT 48,000 grain" systems from different sellers can use different tanks, different resin, different bypass valves and very different warranties. The valve is the same; everything else is up to the seller.
Official Specifications
| Specification | Pentair Rating |
|---|---|
| Continuous flow (15 psi drop, valve alone) | 20 gpm |
| Peak flow (25 psi drop) | 26 gpm |
| Maximum backwash (25 psi drop) | 7 gpm |
| Softener tank size | 6 to 12 inch diameter |
| Regeneration modes | Immediate meter, delayed meter, delayed time clock, day of week |
| Regeneration direction | Downflow or upflow |
| Meter accuracy | 0.25 to 15 gpm, plus or minus 5% |
| Power backup | 48 hours (internal capacitor) |
| Inlet/outlet | 3/4, 1 or 1-1/4 inch |
| Working pressure | 20 to 125 psi |
| Water temperature | 34 to 110 °F |
| Valve body | Fiber reinforced polymer |
| Approvals | UL (powerhead), UL Recognized Component |
From Pentair's 5600SXT specification sheet, part 42749 (PDF); Pentair's European technical sheet gives matching metric figures (PDF). The US sheet is dated 2008, so confirm current details with the seller. Flow figures are for the valve alone; the complete system's flow depends on tank and resin.
The same valve also runs iron, sediment, carbon and neutralizing filters on 6 to 10 inch tanks, which is why it is so common and why replacement parts are easy to find.
Pros and Cons
Pros
- Metered, demand-initiated regeneration
- High 20 gpm continuous flow rating for the valve
- 48-hour power backup keeps settings through outages
- Fully programmable cycles (up to 199 minutes each)
- Very common: parts, manuals and how-to help are easy to find
- Separate-tank design is easy to service and resize
Cons
- Quality of tank, resin and warranty depends on the seller
- No NSF/ANSI 44 certification for the valve itself
- Programming by hand; no app or Wi-Fi
- Separate tanks take more floor space than cabinet units
- DIY setup means getting hardness, capacity and brine fill right yourself
Certification and Testing
We did not find Fleck or Pentair 5600SXT systems in NSF's NSF/ANSI 44 softener listing (NSF listing). Pentair's spec sheet lists UL approval for the powerhead, which covers electrical safety, not softening performance. Because certification applies to a complete system, ask the seller whether their assembled system is certified, by whom, and for the listing number.
We also did not find an independent before-and-after test. SoftPro, a competing softener brand, published a comparison reporting 90 to 95% hardness removal for a Fleck 5600SXT system versus about 97.5% for its own product (SoftPro). Treat that as a competitor's claim. In practice, a correctly sized and programmed ion exchange softener should bring hardness at the tap close to zero; check yours with hardness test strips after installation.
How to Size a Fleck System
Sellers name systems by their capacity at maximum salt (24,000, 32,000, 48,000 and so on). One seller's 5600SXT installation guide shows how capacity and salt use change with the setting (installation guide):
| System (resin) | 0 to 12 gpg | 12 to 25 gpg | 25+ gpg |
|---|---|---|---|
| 32,000 (1.0 cu ft) | 20,000 grains @ 6 lb salt | 27,000 @ 10 lb | 32,000 @ 15 lb |
| 48,000 (1.5 cu ft) | 30,000 @ 9 lb | 41,000 @ 15 lb | 48,000 @ 22.5 lb |
| 64,000 (2.0 cu ft) | 40,000 @ 12 lb | 54,000 @ 20 lb | 64,000 @ 30 lb |
To choose a size: multiply your hardness (in grains per gallon) by the gallons you soften per day. A family using 200 gallons a day at 15 gpg needs 3,000 grains a day. A 48,000-grain system programmed at 41,000 grains, minus a 15% reserve, would regenerate roughly every 11 to 12 days, inside the 14-day override many guides use. A 32,000-grain system set at 27,000 would regenerate about every 7 to 8 days. Either works; a very oversized system rarely reaches capacity, and the day override then triggers regeneration anyway.
The guide also calculates compensated hardness for iron: add 5 grains per gallon for every 1 ppm of iron. Example: 18 gpg plus 2 ppm iron = 28 gpg setting.
Programming the 5600SXT
The seller guide's recommended settings, which apply to most single-tank softener setups (always follow your own seller's sheet if it differs):
| Setting | Typical Value | What It Means |
|---|---|---|
| CT (control type) | Fd (flow delayed) | Regenerates at the set time after capacity is reached |
| C (unit capacity) | From the sizing table | Grains before regeneration |
| H (hardness) | Your compensated hardness | gpg plus 5 per ppm iron |
| SF (safety factor) | 15% | Capacity held in reserve |
| DO (day override) | 14 days | Regenerates at least this often |
| RT (regen time) | 2:00 AM | When regeneration runs |
| BW / BD / RR | 10 / 60 / 12 minutes | Backwash, brine draw, rapid rinse |
| BF (brine fill) | From the sizing table | Sets the salt dose |
The guide warns that reversing the inlet and outlet ports will lead to failure, so check the flow direction before connecting. Set the clock, enter master programming, and step through each value with the arrow and regen buttons. If the softener misbehaves later, see our troubleshooting guide.
Buying Checklist
- Test your water first, including iron, so you can size and program correctly.
- Ask what resin and how much (cubic feet) is in the tank, and whether it is new.
- Check the included parts: bypass valve, brine tank size and safety float, meter type, fittings.
- Read the warranty: valve, tanks and resin are often covered differently, and the seller, not Pentair, usually handles claims.
- Ask about certification for the complete system.
- Plan for iron and sediment: add a sediment prefilter on wells, and a separate iron filter for higher iron. See well water filtration.
- Check local rules on drain connections and whether a permit is needed. Our installation guide covers the air gap and grounding rules.
Fleck vs Store-Brand Softeners
Store-brand softeners from Whirlpool, Rheem, Morton and A.O. Smith are certified under NSF/ANSI 44, with capacity and efficiency verified, and come as complete, ready-to-install units with a manufacturer warranty. A Fleck system offers a higher-flow, widely serviceable valve and separate tanks you can resize, but you depend on the seller for quality and support. If you want verified performance and simple installation, compare store-brand softeners; if you want a standard, serviceable setup and are comfortable programming it, a well-built Fleck system is a solid choice. See all our picks in best water softeners.
Frequently Asked Questions
It is a well-proven control valve with metered regeneration, a 20 gpm continuous flow rating and a 48-hour power backup. How good the complete softener is depends on the seller's tank, resin and warranty.
We did not find Fleck 5600SXT systems in NSF's NSF/ANSI 44 softener listing. Pentair lists UL approval for the powerhead, which is electrical safety, not softening performance.
Multiply your hardness in grains per gallon by daily softened water use. A family using 200 gallons a day at 15 gpg needs 3,000 grains a day; a 48,000-grain system set at about 41,000 grains would regenerate roughly every 11 to 12 days after its reserve.
Pentair rates the valve at 20 gpm continuous (15 psi drop) and 26 gpm peak (25 psi drop). The complete system's flow also depends on the tank and resin.
Set the clock, enter master programming, then set capacity, compensated hardness, a 15% safety factor, a 14-day override, a 2:00 AM regeneration time, cycle times and brine fill, following your seller's sheet.
Use compensated hardness: add 5 grains per gallon for every 1 ppm of iron. For example, 18 gpg plus 2 ppm iron gives a setting of 28.
Last updated: October 2026. Sources: Pentair 5600SXT spec sheet, Pentair technical sheet, seller installation guide, NSF listing, SoftPro (competitor claim).