Hayward Aqua Rite "Check Salt" Light: Low Salt Warnings Explained

What the "Check Salt" Light Actually Means

The Aqua Rite does not have a dedicated salt probe. Instead, it infers salinity by measuring the resistance of the water as current passes through the cell. Lower salt means higher resistance, which the control interprets as a salinity reading.

When the displayed salt drops below about 2700 ppm, the system enters a warning state and the "Check Salt" LED begins flashing. The unit can still generate chlorine, but efficiency is reduced. If salt continues to drop or the reading falls below the system's minimum threshold, the "Check Salt" light goes solid and production stops entirely.

Step-by-Step Troubleshooting

Owner-Level Checks

Confirm the symptom

• Flashing "Check Salt" = low salt, reduced output, but still trying to work.
• Solid "Check Salt" = critically low salt, no generation.

Test salt with an independent method

Do not blindly trust the Aqua Rite reading until you verify it:

• Use a good-quality drop test kit or electronic salt meter.
• Take a water sample from at least 12 inches below the surface, away from returns.
• Record the result in ppm.

Compare test result to Aqua Rite display

• If your test shows salt around 3200 ppm and the Aqua Rite agrees, the light may be a false reading due to cold water, scale, or a cell issue.
• If your test shows salt genuinely low (2500 ppm or less), you need to add salt.

Calculate how much salt to add

Use the standard formula:

Pounds of salt needed = Pool volume in gallons × (target ppm - current ppm) / 1,000,000 × 8.35

For example, to raise a 20,000-gallon pool from 2500 ppm to 3200 ppm:

20,000 × (3200 - 2500) / 1,000,000 × 8.35 = approximately 117 pounds of salt.

Add salt correctly

• Pour salt around the perimeter of the pool, especially in the deep end.
• Brush the bottom to help it dissolve.
• Run the pump continuously for at least 24 hours to ensure complete mixing.
• Do not retest or expect the Aqua Rite reading to update immediately; the averaged display can take a full day to catch up.

Tech-Level Checks

Review recent pool maintenance

Salt can drop due to:

• Backwashing or cleaning a DE/sand filter (lost water = lost salt).
• Draining for repairs or winterization.
• Heavy rain, splashout, or leak repair where fresh water was added.

Check for cold water effects

• Very cold water can affect the salt reading temporarily.
• Use the diagnostic button to scroll to water temperature.
• If the pool is below 60°F and salt tests fine, wait for warmer weather and recheck before adding more salt.

Inspect the cell for scaling

• Heavy scale buildup on the cell plates changes resistance and can throw off salt readings.
• Remove the cell, inspect, and clean if needed.
• Reinstall and check if the reading improves.

Compare average salt to instant salinity

• Use the diagnostic button to find "Instant Salinity" in the scroll.
• If instant salinity is much higher than the main salt display, the system is still catching up to a recent salt addition.
• If both are low and match your test, the reading is accurate and you need more salt.

Verify cell type setting

• Wrong cell type (T-3, T-9, T-15) can skew salt readings.
• Scroll diagnostics to confirm the selected cell type matches the label on your actual cell.

Common Parts That Fix This Problem

Salt (obviously)

Plain pool salt, sodium chloride, typically sold in 40-50 lb bags. Avoid water softener salt with additives.

Turbo Cell

A failing or heavily scaled cell can misread salt. Cleaning usually helps, but if the cell is worn out, replacement restores accurate readings.

Control PCB

Rare, but if multiple cells all show the same wrong salt reading and tests prove otherwise, suspect the board.

Model-Specific Notes

• Aqua Rite targets 3200 ppm and operates in a range of roughly 2700-3400 ppm.
• The salt display is averaged over time, so it reacts slowly to changes. Instant salinity updates faster and can guide you after adding salt.

How To Prevent Low Salt Problems

• Test salt monthly during the season, especially after backwashing, heavy rain, or any water loss.
• Keep a log of salt additions and pool volume so you can calculate corrections accurately.
• Inspect and clean the cell periodically to prevent scale from affecting readings.
• After significant water changes, add salt based on tested levels, not guesswork.

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