Troubleshooting Your Salt Chlorine Generator Low/High Salt Warning Light

As you would expect, Saltwater Chlorine Generators (SCGs) are designed with a means of alerting you to the salinity, or salt content, of your pool. Across different models, it just about universally takes the form of a warning light. The lights can be specific to high or low salt, but for some models, there is just one light that simply alerts you to the salinity being outside of the correct range. While some SCGs offer a digital readout of the measured salinity, they still utilize warning lights to alert you that the system has a specific issue due to high or low salt conditions.

Just like traffic lights, green is good (or, for some SCG models, no light), and red is a problem. Other variations, like blinking or slow and fast blinking, are brand and model specific. For some models, blinking means there is a slight issue and the system is still working, but for a small number of other models, blinking means there is a severe issue. Your owner’s manual is your friend.

A Few Realities About Pool Salinity

• Your salinity only decreases when water is splashed out, carried out (on your person), drained out, leaked out, or backwashed out of the pool.


• Evaporation leaves the salt behind.


• SCGs do not consume salt. They only “borrow” it. In fact, theoretically starting at 3,500 ppm salinity, a generous 5 ppm free chlorine level will have borrowed only 8 ppm, leaving you in theory at 3,492 ppm salinity. On top of that, those 8ppm would come right back if you turn the SCG off and let the FC drop to zero (don’t really do that!)

A Few Realities About Salinity Testing

When your SCG measures salinity, it is inferring the salinity from a measure of the water's conductivity. The number it figures will be close enough but won’t necessarily match another form of measurement.

• Handheld electronic testers work on the same principle and measure conductivity rather than “counting” salt ions. Even when properly calibrated, an SCG and a handheld tester may differ by +/- 200-400 ppm.


• “Drop count” titration test kits are considered the gold standard for accuracy and provide the most reliable results for achieving real-world certainty regarding your pool’s salt levels.If you need to know precisely what your pool water’s salt level is, you’ll want to compare it to results from this type of salinity testing.


• Test strips are the least precise method. They require you to judge and match colors which indicate a range of possible salinity levels.


• Aged test strips or reagents can throw off results. Factors such as heat, light, humidity, and exposure to air can degrade the accuracy of these methods.


• Pool stores essentially use the same or similar methods with comparable accuracy.


• Additive uncertainty: The uncertainty levels between one source and another can be additive; if my testing is +/- 150 ppm and yours is +/- 200 ppm, we have the potential to be off by +/- 350 ppm.

First Step: Verify Your Salinity

With all of the above in mind, test the salinity of your pool water to help determine if the indicated problem is with your water’s salinity or with the equipment. Is your pool water’s salt level actually out of range, or not? If your result differs materially from the SCG’s reading or light, take the opportunity to test the water again with a different method to be certain. Essentially, the first step is to be absolutely positive about what the water’s actual salinity level is.

Always seek confirmation of your salinity before
adding salt or draining and topping off your pool

If The Pool’s Actual Salinity is Out of Range

Raising Salinity

Refer to a salinity chart either here or from your manual and add the required amount of salt. This type of chart will help you determine how much salt to add based on your current salinity level and your pool size.

When adding salt to the pool, distribute it throughout the main body of the pool, avoiding any piles of salt. Do not add salt through the skimmer. Run your pump for at least 24 hours to help ensure it all dissolves and distributes equally throughout the water. If you have any accumulation of undissolved salt, then move it about with your pool brush to help it dissolve as quickly as possible.

Although the warning light might clear quickly in some cases, you should give the pool at least a full day’s circulation before measuring salinity at the level you are adjusting it to.

Lowering Salinity

Less commonly, you may need to lower the salt level of the pool. Remember that salt chlorinators don’t generate salt; if your salt level is high, this means that too much salt was added. Lowering the salinity will entail calculating how far to lower the pool level before topping off with freshwater.

To reduce salinity by a given percentage, you have to remove that percentage of the pool water and replace it with fresh water. In other words, if you want your salinity to be 25% less than your current salinity, you need to remove 25% of the water and refill. This can be based on how many gallons are in your pool, and it can also be based on the water level of your pool IF you have an accurate estimate of your pool’s average depth.

Example

You’ve confirmed that your salinity is 4,670 ppm. Since your SCG specifies 3,000-4,000 ppm, you want to lower the salinity to 3,500 ppm (a reduction of 1,170 ppm). Your pool’s average depth is 5’.

Calculation: 1,170 / 4,670 = 0.25 (25% of water should be removed).

Depth Adjustment: 5’ x 0.25 = 1.25’ (approx. 15 inches).

If The Pool’s Actual Salinity Is Correct

There are several common possibilities for why a salt chlorinator might get false salinity readings, including a dirty cell (and salinity sensor), an incorrect cell type setting, or air in the cell.

• Clean the Cell: You may or may not also be getting a “check cell” / “cell maintenance” light. Even if not, start with a thorough cell cleaning (multiple times in a row if necessary, until when you clean it with freshly mixed solution you no longer immediately see any “fizzing”). Scaling and calcium deposits on the cell blades or particularly on the sensor will cause many models to read a lower-than-actual salinity level.


• Check Cell Type or Cell Version: This is a brand/model specific issue, but for systems that have provisions for designating the cell capacity, an incorrect setting will almost certainly give incorrect salinity readings. This is also typically the only issue that can cause a higher-than-actual salinity reading.


• Address Air in the Cell: Air collecting in the salt cell can give you false low salinity readings. If you have a transparent cell housing, look for an air pocket inside the cell.
• If you see air in the cell, or have an opaque cell, you can raise your pump speed to its maximum setting and observe whether the air can be moved through the cell and whether the warning goes away. Some models may need to be turned off/on once the flow is higher in order to clear the error and cause them to re-check their diagnostics. When installed horizontally, one common style salt cell (see images) can minimize the likelihood of an air pocket inside and stay flooded with water more easily simply by rotating the cell. (IMPORTANT: only do so if manufacturer instructions allow this)
• 
• Air accumulating in the cell can be an indication that waterflow is too low or that you have a suction-side leak introducing air into the plumbing. Check the water level in the skimmer and inspect all fittings and connections between the pool and pump.


• Water Temperature: Cold water temperatures can also cause salinity readings to read lower than they might actually be. If your water is cold and approaches the 50’s F or lower, it's very possible this can be at play. Older salt chlorinators or models without a built-in temperature probe can be more prone to this.


• Cables & Connections: Take the opportunity to inspect any cell cable connections to ensure they are clean, tight, and free of damage. It is possible for a poor connection to influence the salinity reading. Older salt chlorinators or models which work internally on lower voltages can be more prone to this.


• Cell Lifespan: If all of your other troubleshooting checks out, and also if your cell is old and has received substantial use over the years, that means the cell itself is likely nearing the end of its lifespan.

Going through this range of possibilities should help you identify and resolve the problem that is causing the low or high salt warning light. Otherwise, we are available Mon-Thu: 9-4:30 or Fri: 9-3PM Central Time. Call (866) 766-5243, and a member of our support team will try to assist you, or you can request assistance online.