A failing salt cell shows signs like low chlorine production despite proper salt levels, calcium buildup on plates, error codes on the control unit, or visible damage to the cell housing. Test by checking amperage draw and inspecting the plates for scaling or corrosion.
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Your salt cell is likely bad if you're experiencing low chlorine production despite proper salt levels (3000-4000 ppm), seeing calcium buildup on the electrode plates, getting error codes from your control unit, or noticing visible damage to the cell housing. The most reliable test is checking the amperage draw - a good cell should draw within 10% of its rated amperage at proper salt levels.
Start your diagnosis with a thorough visual inspection of the salt cell. Remove the cell from your plumbing system and examine it closely under good lighting.
Heavy white, chalky deposits on the electrode plates indicate calcium scaling. While some scaling is normal and can be cleaned, excessive buildup that doesn't come off with muriatic acid cleaning suggests the cell is nearing end of life. The plates should have a dark metallic appearance when clean - if they remain white or gray after acid cleaning, replacement is needed.
Look for cracks in the cell housing, broken or missing electrode plates, or loose connections. Any physical damage to the cell body or internal components means immediate replacement. Check the threaded unions for stress cracks, which can cause water leaks and electrical issues.
Healthy electrode plates should be evenly spaced and relatively straight. Warped, bent, or corroded plates indicate the cell has reached its operational limit. Missing pieces of coating on the plates or visible metal corrosion are definitive signs of failure.
Beyond visual inspection, performance testing gives you concrete data about your salt cell's condition.
This is the most accurate diagnostic test. With your salt cell installed and the system running at 100% output, use a clamp-on ammeter to measure the amperage draw on the cell's power cable. Compare this reading to the manufacturer's specifications - typically 5-7 amps for residential cells. If the draw is more than 10% below rated amperage, the cell is failing.
Conduct this test when your salt level is confirmed between 3000-4000 ppm. Turn your salt system to maximum output for 24 hours, then test free chlorine levels. A healthy cell should produce 1-2 ppm of chlorine per day in an average 20,000-gallon pool. Consistently low production despite proper salt levels indicates cell deterioration.
Modern salt systems provide valuable diagnostic information through their control panels and displays.
Pay attention to any error codes displayed on your control unit. Common codes include "Check Cell," "Low Salt" (when salt levels are actually correct), "High Salt," or "Inspect Cell." These codes often indicate the system isn't reading the cell properly due to internal cell problems.
If your control panel shows erratic salt level readings that don't match manual test results, the cell's ability to conduct electricity may be compromised. This often happens as the electrode coating deteriorates.
Your pool's water chemistry can reveal salt cell problems before they become obvious.
Despite running your salt system at high output with proper salt levels (3000-4000 ppm), you consistently measure low free chlorine levels below 1 ppm. This is often the first sign pool owners notice when their cell begins failing.
A functioning salt cell naturally raises pH during chlorine production. If your pH has stopped rising or becomes easier to maintain, it might indicate reduced cell activity. However, this should be considered alongside other symptoms since pH stability can have many causes.
Salt cells have finite lifespans that depend on usage and maintenance.
Most quality salt systems track cell operating hours. Residential cells typically last 10,000-15,000 hours, which translates to 3-7 years depending on your climate and usage. If your cell is approaching these hours and showing performance issues, replacement is likely needed.
Cells requiring cleaning more frequently than every 3 months, or cells that don't respond well to muriatic acid cleaning, are showing signs of wear. If you're cleaning monthly and still seeing poor performance, the cell is probably failing.
When home testing is inconclusive, professional diagnostics can provide definitive answers.
Pool professionals can perform load testing using specialized equipment that measures the cell's ability to maintain voltage under different electrical loads. This test reveals internal resistance problems not visible during basic amp draw testing.
Using conductivity meters, technicians can measure how effectively your cell transfers electrical current through the salt water. Poor conductivity despite adequate salt levels indicates electrode deterioration.
Warning: Always turn off power to your salt system before removing or inspecting the cell to prevent electrical shock.
Regular maintenance extends cell life and helps you identify problems early. Clean your cell every 3-4 months using a 10:1 water-to-muriatic acid solution, maintaining your pool's pH between 7.2-7.6, and keeping salt levels stable between 3000-4000 ppm.
Monitor your cell's amperage draw monthly during swimming season to establish baseline readings. Document cleaning dates and any performance changes to track deterioration patterns over time.
Salt cells are generally not repairable - they're consumable components designed for replacement. If your diagnostic testing confirms poor performance and the cell is over 3 years old or has significant operating hours, replacement is the most cost-effective solution. Attempting repairs on salt cells typically provides only temporary fixes and isn't recommended by manufacturers.
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