Swimming Pool Blog
by Mark Garcia April 30, 2016
How do you know when your salt chlorinator is not working? One day your salt cell may just up and quit, but usually it's a gradual deterioration of chlorine output that leads people to wonder if the salt cell is still working?
Salt cells generally last 3-5 years, sometimes more or less. Lifespan varies according to factors like water chemistry and temperature, regular cleaning of the cell, cell size in relation to pool size and a bit o' luck.
Many inground salt control panels will display a 'Check Salt Cell' error code or indicator light, but these aren't like a Check Engine light, they are simply reminders to inspect and clean the cell, and pop up every 500 hrs or so.
So then, how do you know when the salt cell is dead, or can a salt cell output be measured?
Basic Salt Cell Troubleshooting
1. Check Power: The Salt Cell is powered by the control panel, and the before it reaches the salt cell, the incoming 115/230 VAC is stepped down to about 7-9 VDC, by a transformer. A simple way to check that power is on is to feel the power cord for warmth. If the control panel has no indicator lights, that's a good sign of no power. Check for a tripped circuit breaker or GFCI outlet test button. Many salt chlorinators also have a fuse inside the cabinet, designed to blow in the event of power overload, or a lightning strike.
2. Check Water Flow: The Salt Cell needs a certain amount of water flow to operate effectively. Full featured salt systems use a Flow Switch or sensor to measure water flow entering the salt cell, and will open the ciruit when flow rates are below a minimum threshold. Flow rates can be reduced by clogged pump or skimmer baskets, dirty filter, or closed directional valves.
3. Check Salt Level: The Salt Cell needs a certain amount of salt in the water to convert the salty water to chlorine. Each salt cell is calibrated to work within a certain range of salinity, generally around 3000 ppm. Full featured salt systems use a salt sensor and display the measured salt level, or have an indicator light or error code to let you know when the salt level drops below the minimum threshold. Salt sensors can be faulty however, so it's always a good idea to check your salt level with salt test strips, to be sure your salt level stays within the proper range.
4. Check Water Balance: Your pH, alkalinity and calcium hardness should all be within range so that the created chlorine has the most efficacy, or killing power. Low pH can accelerate the activity of chlorine, burning off more rapidly, and high pH can reduce the activity, making your chlorine sluggish and less effective. Perhaps more importantly, the cyanuric acid (aka conditioner or stabilizer) level must be 20-50 ppm for outdoor pools. Sunny pools that don't use stabilizer can often dissipate free chlorine as fast as it's being put into the water.
5. Inspect Salt Cell: The Salt Cell needs to be cleaned regularly to remove calcium deposits that slow water flow and bridge the gap between metal plates, preventing the electrolysis from happening. Full featured salt systems are self-cleaning, by reversing polarity on the metal plates, to slough off the collected calcium which is swept away by the water flow. However, even self-cleaning cells need regular inspection, and perhaps occassional cleaning. Also be sure that no debris is trapped inside of the cell, some pool filter problems can release small debris.
Also important is to clean the electrode terminals, which can develop a corrosion similar to car battery terminals. Terminal corrosion can be removed with an old toothbrush dipped into an acid solution. If you have a clear housing around your salt cell, you can inspect the cell for cleanliness without dissassembly. When operating, you should also see very tiny bubbles inside the chamber, producing what looks like cloudy water - that's chlorine being created! If you don't have a clear housing to view chlorine being made, many salt cells can be removed from the housing and placed in a bucket of salty pool water. Turn it on and look for tiny bubbles or cloudy water being created.
Advanced Salt Cell Troubleshooting
1. Check Voltage on Salt Cell: The Salt Cell needs the proper voltage to operate correctly. Check for loose wire connections on terminals (with power turned off). Check the power cords for discoloration or damage. Check incoming voltage with a multimeter to be sure it matches the specs on the controller label, or the owner's manual. Checking the volts at the salt cell terminals is also a good idea. This is done with the salt cell in Boost mode, or otherwise on a High setting. Set your multimeter to DC volts, and compare against the specs printed on the label or in the owner's manual.
2. Check Sizing of Salt System: Salt Cells are sized according to the gallons in the pool, but it is common practice for manufacturers to size a salt cell as if it was operating 24 hrs per day. If your salt cell is rated for 25000 gallons, and you actually have a 25000 gallon pool, it may have a hard time keeping up, especially in very cool or very warm water temperatures, or in the presence of phosphates.
3. Check Pool for Phosphates: Phosphates and nitrates in the pool water provide a nutrient rich food for algae, which uses up your chlorine almost as fast as it's created. Test the pool for the presence of Phosphates, and if over 300 ppb, you should use a Phos-Free type of chemical phosphate remover. Pools with algae problems or ineffective filters, can likewise create a high chlorine demand that salt cells may have trouble keeping up with.
4. Check Circuit Board: In many cases, the PCB (printed circuit board) is what is preventing the salt cell from producing chlorine. If you have no power reaching the salt cell, and the sensors (salt, temp, flow) are not causing an open circuit, something on the circuit board (resistors, capacitors and limiters) could be burned out or otherwise causing an open circuit (the problem lies where the power dies). Often times, just looking closely at the circuit board can reveal a problem, when something looks burned or cracked. If you are handy with a soldering tool, circuit board components can be replaced.
5. Check Amps on Salt Cell: Using a clamp-on amp meter, you can test the amperage of the salt cell, to be sure it matches the label on the controller, or the owner's manual specs. Like voltage tests, the amperage test is done when the unit is operating at boost or high levels. Generally speaking, the amp output will decrease as Salt Cells reach the end of their lifespan.
Thanks for Reading!