Hayward AquaRite 900 Pool Has Low Chlorine Even With System On

What "Low Chlorine With System On" Actually Means

The AquaRite 900 can only produce chlorine when the pump is running and it is actively generating. If the pump runs for only a few hours per day, or the output percentage is set very low, the total chlorine production may not keep up with demand.

Additionally, chlorine effectiveness and longevity depend heavily on water chemistry. If pH is high, stabilizer is low, or the pool has heavy organic load, chlorine can disappear almost as fast as it is made.

Step-by-Step Troubleshooting

Confirm the system is actually running

1. Look at the Generating light. It should be on steady during much of the pump cycle.
2. If it is often off, revisit the "not generating" troubleshooting first.

Check desired output percentage

1. Note the current output setting on the front dial or in automation.
2. For many residential pools in full sun, output in the middle range is common. Very low settings might not keep up with demand.
3. Make small increases (10-20%) and monitor over several days instead of jumping from very low to maximum.

Check pump run time

1. Determine how many hours per day the filter pump actually operates.
2. At least one full turnover per day is a baseline, with more time needed for higher bather loads.
3. If you only run the pump a few hours at low speed, you will not generate much chlorine regardless of the output percentage.

Test stabilizer and pH

1. Check cyanuric acid. Outside of special cases, the range around 30 to 50 ppm is a reasonable target.
2. Very low stabilizer makes it almost impossible to hold chlorine in strong sun.
3. Keep pH around the recommended range to keep chlorine effective.

Look for visible algae or heavy debris

Any tint of algae or heavy organic content can consume chlorine as fast as the cell produces it. In these cases you may need to shock with traditional chlorine and clear the problem before relying on the salt system again.

Evaluate cell output

1. Use diagnostics to read cell voltage and current while Generating is on.
2. Compare to typical values for a healthy cell at the present salt level.
3. If current is significantly lower than expected, the cell may be scaled or worn.

Inspect and clean or replace the cell

Follow the Inspect Cell cleaning procedure. If output remains low in correct chemistry and salt, consider replacing the cell.

Review overall system sizing

Confirm that the cell model is appropriate for the pool volume. Running a small cell at maximum output for a large pool can still result in low chlorine.

Check for constant dilution

Look for autofill problems, leaks to waste, or other issues that constantly replace pool water. This can dilute chlorine and salt continually.

Common Parts That Fix This Problem

• None in many cases; tuning runtime, output, and stabilizer does the heavy lifting
• Chlorine shock and algaecide in the short term if the pool already has a problem
• Replacement cell if diagnostics and age indicate poor production

Model-Specific Notes

• Short filter pump time, low stabilizer, low salt, and high salt are explicitly listed as possible causes for low or no chlorine residual. Work through those first.
• The AQR940 is rated for larger pools than the AQR925. Using the correct model for the pool size matters.

How to Prevent Chronic Low Chlorine

• Set a realistic baseline for pump runtime based on climate and bather load.
• Keep stabilizer and pH in range year round.
• Do not hesitate to temporarily supplement with liquid chlorine during peak demand periods such as parties or heat waves.
• Keep filters and surfaces clean so the cell's output is not constantly consumed by preventable load.