Hayward AquaRite 900 Not Generating Chlorine: Gen Light Off or Flashing

What This Light Actually Means

When several conditions are true at once—pump running with adequate flow, flow switch closed, water temperature in the allowed band (roughly above 50°F), salt within range, no active shutdown errors, and main switch in AUTO or SUPER CHLORINATE—the controller will apply current to the cell at whatever percentage you have set. While it is actively doing so, the Generating light is steady.

If the controller senses that water is too cold or too hot, it will stop energizing the cell and flash the Generating light as a temperature alarm instead of as a duty-cycle indicator.

Step-by-Step Troubleshooting

Rule out simple duty-cycle behavior

At low output settings, the unit cycles on and off while the pump is running.

1. Confirm the "Desired Output %" knob position or the percentage in the automation menu.
2. If set to a low value (for example 10–20 percent), the Generating light will only be solid for a small fraction of the run time.

Wait a few minutes with the pump running. If the light periodically turns on and off and no error LEDs are lit, this may be normal operation.

Check the main switch and automation status

1. Look at the main switch: OFF, AUTO, or SUPER CHLORINATE.
2. If it is OFF, the Generating light will remain off by design.
3. If the REMOTELY CONTROLLED light is on, the automation system is in charge and may have output set to zero.

Use the automation panel to confirm chlorinator settings when REMOTELY CONTROLLED is lit.

Look for a flashing Generating light

If the light is flashing:

1. Press the diagnostic button until you see the water temperature on the display.
2. Compare it to actual pool water temperature.

If the displayed temperature is around the low cutoff or clearly wrong, the unit is likely in temperature lockout and will not generate until water warms. You can temporarily force production by switching to SUPER CHLORINATE, but this is not a permanent fix for very cold water.

Review other LEDs and diagnostic data

1. Check for NO FLOW, CHECK SALT, HIGH SALT, or INSPECT CELL lights. Any solid shutdown light will prevent generation.
2. Press the diagnostic button in sequence and note cell voltage, cell current, and instant salinity.

If voltage and current are both near zero while the unit claims to be generating, you likely have a cell or board problem.

Confirm pump, valves, and flow switch

Even if NO FLOW is not lit, circulation issues can confuse the system.

1. Make sure the pump is fully primed and you have return flow to the pool.
2. Confirm suction and return valves are open to the pool, not bypassed.
3. Check the flow switch orientation: the arrow on the hex body must point in the direction of water flow, and there must be at least 12 inches of straight pipe feeding it.

If flow is marginal, correct that first.

Test SUPER CHLORINATE mode

With pump running and water within range:

1. Flip the main switch from OFF to SUPER CHLORINATE.
2. Wait through the startup delay.
3. Watch whether the Generating and SUPER CHLORINATE lights come on solid.

If the unit still refuses to generate in this mode and no shutdown lights are on, suspect a deeper board or cell issue.

Common Parts That Fix This Problem

• Temperature sensor / cell assembly if the reported water temperature is clearly wrong and the unit is stuck in temperature lockout
• Flow switch when intermittent flow reporting leads to confusing behavior between NO FLOW and Generating
• Chlorinator cell if diagnostics show abnormal current draw even when everything else is in range
• Control board when readings are obviously wrong, or the Generating light never comes on despite good power, flow, salt, and a known-good cell

Model-Specific Notes

• AquaRite 900 units stop generating automatically when water temperature falls below roughly 50°F to match reduced chlorine demand and protect the cell. You can override this temporarily with SUPER CHLORINATE, but that is not recommended as a long-term mode in cold water.
• When connected to Hayward, Pentair, or Polaris automation, the front-panel output dial is disabled. Look at the REMOTELY CONTROLLED light to know which device is in charge.

How to Prevent This Issue From Coming Back

• Set realistic pump runtimes and output percentages based on season instead of leaving the unit at a high setting year-round.
• Keep water chemistry in range so chlorine demand matches what the system can produce.
• Educate owners that cold water periods will naturally reduce generation and that this is normal.
• Install and maintain the flow switch with the required straight run so it gives consistent feedback.