Hayward AquaRite 900 "Check Salt" Light: Low Salt and Weak Output

What the "Check Salt" Light Actually Means

The AquaRite 900 estimates salt level by measuring how the cell conducts current under a known voltage. It displays an average salt value by default and uses that to decide whether to reduce or stop output. When the measured salinity drops below a threshold, the Check Salt light begins flashing to warn of reduced efficiency. If salt falls further, the light stays solid and the unit shuts down to protect the cell.

The system is designed to work around the low three thousand ppm range. Below that the cell has to work harder and chlorine production suffers.

Step-by-Step Troubleshooting

Owner-Level Checks

Confirm salt level with a test

1. Use a drop based salt test kit or a reliable digital meter.
2. Take a sample from elbow depth away from returns and skimmers.
3. Compare the tested salinity to the display salt value. If the test is low, your pool really does need salt.

Check the warning state

1. Note whether the Check Salt light is flashing or solid.
2. If it is flashing, the unit is still producing but at reduced efficiency.
3. If it is solid, chlorine generation has stopped until salt is corrected.

Add salt if truly low

1. Use pool grade sodium chloride as specified in the manual.
2. Calculate how many pounds you need based on pool volume and current vs target salinity.
3. Broadcast the salt across the shallow end and brush to help it dissolve, with the pump running.
4. Do not pour salt directly into the skimmer or through a heater.

Retest and give the system time

1. Let the pump circulate for at least 24 hours.
2. Retest with your kit and compare to the display.
3. Expect the controller's average salt to lag a bit behind the actual instant reading.

Tech-Level Checks

If Check Salt is on but your test says salt is fine:

Verify Turbo Cell type

1. Use the diagnostic button sequence to step to the t code.
2. Confirm it matches the installed cell model shown on the cell label.
3. If it is wrong, correct it using the main switch and diagnostics steps in the manual, then recheck salt.

Use instant salinity and update the average

1. Use the diagnostic button until you see the instant salinity value (negative salt number).
2. If the instant value makes sense and the average is stale, you can "update" the average by following the manual's short sequence with the main switch and diagnostic button.
3. This effectively syncs the displayed average to what the cell is currently reading.

Inspect and clean the cell

1. With power off, remove the cell and look for white or tan deposits on the plates.
2. If moderate or heavy scale is present, clean the cell per the manual's procedure using diluted acid in a plastic container, keeping the cable end out of the solution.
3. Rinse thoroughly, reinstall, and recheck readings.

Evaluate cell age

A worn cell draws less current for a given voltage, which the controller can interpret as low salt. If salt tests are correct, the cell is clean, and the Turbo Cell type is correct, but the Check Salt light keeps returning, the cell may be nearing the end of its life.

Common Parts That Fix This Problem

• Pool grade salt to raise salinity to the recommended band
• Replacement Turbo Cell when the original is worn out or producing a persistent false low salt condition
• In rare cases, a replacement control board if salt readings are erratic and not tied to chemistry or the cell

Model-Specific Notes

• The AquaRite 900 series supports several cell sizes. The correct t code must be matched to models like TCELL925 or TCELL940 as shown in the diagnostics.
• Always confirm salt with a separate test before making big additions. That saves you from overshooting.

How to Prevent Check Salt Problems

• Log how much water you lose to backwashing, draining, and splash out. All of that lowers salt.
• Test salt a few times per season instead of only when the light comes on.
• Keep pH and calcium in range to minimize scale so the cell reading stays accurate.
• Make sure the correct Turbo Cell type is set whenever a cell or board is replaced.