Pool salt cells use electrolysis to convert dissolved salt (sodium chloride) into chlorine gas and sodium hydroxide. The chlorine sanitizes your pool while the sodium hydroxide raises pH, creating a continuous chlorination cycle.
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A pool salt cell works through electrolysis - passing electrical current through salt water to split sodium chloride molecules into chlorine gas and sodium hydroxide. The chlorine sanitizes your pool water while the sodium hydroxide raises pH. This process happens continuously as water flows through the cell's electrolytic plates, eliminating the need to manually add chlorine.
The magic happens inside your salt cell's titanium plates coated with precious metals like ruthenium or iridium. Here's the exact chemical process:
When your pool pump circulates salt water through the cell, the control unit sends low-voltage DC current (typically 3-7 volts) through the electrolytic plates. This electrical current breaks apart the salt molecules (NaCl) in a process called electrolysis:
At the anode (positive plate):
2Cl⁻ → Cl₂ + 2e⁻
This creates chlorine gas that immediately dissolves into the water as hypochlorous acid - the same sanitizing agent you get from liquid chlorine.
At the cathode (negative plate):
2H₂O + 2e⁻ → H₂ + 2OH⁻
This produces hydrogen gas (which escapes) and hydroxide ions that raise your pool's pH.
Your salt cell requires a specific salt concentration to function properly - typically 3,200-3,800 ppm (parts per million). This is about 1/10th the salinity of ocean water. Too little salt and the cell can't generate enough chlorine. Too much salt can damage the cell and create excessive chlorine production.
To achieve proper salt levels, add 240 pounds of pool salt per 10,000 gallons to reach 3,200 ppm from zero. Always use pure sodium chloride pool salt - never table salt or rock salt which contain additives that can damage your cell.
Modern salt cells include a crucial self-cleaning feature called reverse polarity. Every few hours, the control unit reverses the electrical current, making the anode become the cathode and vice versa. This process removes calcium scale buildup that naturally occurs during electrolysis.
Without this self-cleaning cycle, calcium carbonate would coat the plates and reduce chlorine production. The white flaky deposits you might see in your pool after cleaning cycles are normal calcium scale being shed from the plates.
Your salt cell doesn't run at full capacity 24/7. The control unit regulates chlorine production by adjusting the electrical current and cycling the cell on/off. Most systems allow you to set output from 20-100% based on your pool's chlorine demand.
During peak swimming season, you might run at 80-100% output. In cooler months, 30-50% may be sufficient. The key is maintaining proper free chlorine levels of 7.5% of your CYA (stabilizer) level - if you have 50 ppm CYA, target 3.8 ppm FC.
Salt cells work most efficiently when water temperature exceeds 60°F. Below this temperature, chlorine production drops significantly. Most systems automatically shut off below 50-55°F to prevent damage.
Proper water flow is critical - typically 20-60 gallons per minute depending on cell size. Too little flow causes hot spots that damage the plates. Too much flow doesn't allow sufficient contact time for electrolysis.
Unlike traditional chlorination, salt cells inherently raise pH because the electrolysis process produces sodium hydroxide (lye). This is why salt water pools require more frequent pH adjustment with muriatic acid.
Expect to add 1 quart of muriatic acid per 10,000 gallons weekly to maintain pH between 7.4-7.6. Keep total alkalinity lower than traditional pools - 60-80 ppm - to help control pH rise and prevent excessive scaling on the cell plates.
Salt cells have finite lifespans measured in operating hours, typically 8,000-10,000 hours or 3-7 years depending on usage. The precious metal coating gradually erodes with each electrolysis cycle.
Signs your cell needs replacement include inability to maintain chlorine levels even at 100% output, visible plate erosion, or error codes indicating low cell voltage. Regular cleaning and proper water chemistry extend cell life significantly.
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