No Chlorine From Your Salt System? Here’s Why

Saltwater pools promise steady chlorine with less hassle, yet many owners wake up to zero readings and a confused control panel. The real problem rarely comes from a single fault; it’s a system of limits tied to water chemistry, temperature, flow, and equipment age. Start at the cell: scale on the plates acts like insulation that blocks current and slashes production. Even when your controller doesn’t flash a “clean cell” alert, thin calcium film can cripple output. A gentle acid bath using the ratio in your owner’s manual removes scale without stripping plate material. Over‑acid washing shortens cell life, so avoid strong mixes and long soaks. Make a habit of visual checks, especially with clear‑lid models, and plan light cleanings before peak season.

Next, verify the salt level with a trusted tool rather than the panel alone. Controllers can drift or lie when a cell ages, showing false low or high readings that lock out generation. A handheld digital salinity meter pays for itself by stopping guesswork. Most systems need 2800 to 3500 ppm to operate, with 3000 ppm as a practical target. Too low and production stalls; too high and some units throw a high‑salt error and shut down until they recalibrate. Confirm the pool’s true salinity, then compare to what the unit “thinks” it sees. If those numbers disagree by a lot, you may be looking at a dying cell or sensor issue rather than bad water.

Temperature quietly rules chlorine production. Electrolysis hates cold water, and most generators throttle or stop in the low 60s. That’s why spring salinity checks matter more than winter tinkering. If your climate keeps water cold, bridge the gap with a tablet floater or occasional liquid until temps rise. This tactic not only maintains a sanitizer floor but also adds a small bump of cyanuric acid you’ll want in summer sunlight. Trying to force a generator to work in cold water leads to frustration and misdiagnosis, so time your adjustments when the cell can actually run.

Aging cells create the most confusing symptoms. Expect three to five years depending on runtime, output percentage, and scale exposure. Brands signal decline differently: some show chronic low‑salt warnings, others blink service codes or display life‑percent lights. When you suspect end‑of‑life, confirm at a pool store, check voltage and amperage against spec, or swap in a known‑good spare cell if you service many pools. Physical damage is rarer but real: cracked or chipped plates and failed internal sensors can mimic chemistry problems. If a sensor glitches, a careful double acid rinse sometimes resets deposits on probes, but damaged plates or persistent fault codes usually mean replacement.

Flow is the safety gate that many owners overlook. A chewed flow‑switch wire, a failed paddle, or a clogged filter can all convince the system there’s no water moving, and it will refuse to generate to prevent a dry‑fire event. Variable‑speed pumps add another layer: if RPMs sit below roughly 1800 on many setups, the cell won’t see enough flow to activate. Keep your filter clean, set a reliable high‑RPM window when you expect production, and place the cell where it enjoys stable, straight‑through flow. If your panel shows a red or flashing flow light, inspect wiring, replace suspect sensors, and verify actual gallons per minute before chasing chemistry ghosts.

Production math decides whether a healthy system can meet demand. The output spec, like 1.4 pounds of chlorine per day from a common cell, assumes 24 hours at 100 percent with robust flow. Real pools run fewer hours at lower speeds and lower output, so production drops fast. To benchmark, run one controlled 24‑hour cycle at full speed and 100 percent, then test free chlorine. If levels jump as expected, your problem is runtime or percentage, not hardware. From there, taper hours, RPMs, and output until you land on a steady target that matches bather load, sun exposure, and pool volume. When in doubt, err slightly high on runtime for stable sanitation, then trim back in small steps.

Finally, separate system faults from water issues you’ll cover on your broader maintenance plan. Cyanuric acid that’s too low burns off chlorine; too high slows it down. High organic load, algae onset, or residual ammonia can sponge up new chlorine as fast as you make it. Once the generator is confirmed healthy and the flow is right, dial in stabilizer, brush and filter, and shock if needed. Treat the generator as one engine in a larger machine. With clean plates, verified salinity, warm enough water, solid flow, and realistic production settings, a salt system becomes what you wanted from day one: quiet, consistent, and dependable.