Pool Water Chemistry: Troubleshooting Guide

Pool water chemistry is complex, and having the perfect balance of all the different key parameters is important to ensure a safe environment for bathers. Here we discuss some of the top issues with swimming pool water, potential causes of these and how to troubleshoot including key water chemistry tests to perform.

Pool Water Problems and Solutions

Swimming pool water can suffer from multiple issues, a lot of these stem from an imbalance of key water chemistry parameters. The Lumiso Pooltest Expert is a multi-parameter photometer suitable for testing multiple times daily, quickly and accurately across key and troubleshooting parameters. Lumiso Pooltest Expert offers tests for all of the chemical parameters mentioned in this guide, as well as many other important parameters for pool water testing.

1. Pool Water going Green

There are a few potential causes for pool water turning green, most link to signs of poor water chemistry. Usually, a green colour will indicate either a low disinfectant residual or high cyanuric acid levels.

Key parameters to check: Chlorine, pH and cyanuric acid


  • Carry out a chlorine and pH test to ensure both of these key parameters are within the ideal range (ideally 7.2-7.4 for pH, free chlorine residual of 1.0 mg/L).
  • Check the cyanuric acid levels (recommended level is 25–50 mg/L) and reduce if required by diluting the pool water.

2. Salty Taste in Water

If bathers are reporting a salty taste from the pool water, this is likely due to the TDS levels in the pool being too high.

Key parameters to check: TDS


  • Check TDS levels using Pool Electrochemical Meter (recommended level is no more than 1000 mg/L higher than that of the mains water, up to a maximum of 3000 mg/L).
  • Reduce TDS levels in the pool using dilution if required.

3. Cloudy Water

Highly turbid water usually indicates an imbalance in pool chemistry parameters, specifically linked to a lack of disinfection control. High combined chlorine values can cause a reduction in water clarity, this could be caused by any of the parameters which affect water balance. Inefficient coagulation and flocculation processes, or inadequate filtration can also cause highly turbid water.

Key parameters to check: Turbidity, water balance


  • Check the turbidity of the pool water (usually recommended that the turbidity level in a pool should be no more than 0.5 NTU).
  • Carry out a water balance test to ensure effective disinfection and adjust parameter levels as required.


4. Signs of Erosion of Grout in between Tiles

Potential causes of erosion of grout in the swimming pool include poor water balance, low calcium levels or high sulfate levels.

Key parameters to check: Calcium hardness, sulfate, water balance


  • Carry out a sulfate test and adjust down to acceptable levels.
  • Carry out a full balanced water test and adjust levels accordingly.

5. pH Difficult to Control

If the pH of the swimming pool is difficult to control, this could be pH ‘bounce’ due to low alkalinity levels.

Key parameters to check: Total alkalinity


  • Carry out a total alkalinity test and adjust to required level (recommendation is between 80–200 mg/L)
  • If alkalinity levels are too low, sodium bicarbonate can be added to increase readings.

6. pH Difficult to Adjust

If the pH level of the water does not seem to be changing, even after addition of chemicals, this may be due to pH ‘lock’. This happens when the pool alkalinity is too high.

Key parameters to check: Total alkalinity


  • Carry out a total alkalinity test and adjust to required level (recommendation is between 80–200 mg/L).
  • If alkalinity levels are too high, dilution can be used to reduce the total alkalinity.

7. Complaints of Stinging Eyes and Skin Irritation

Eye and skin irritation is usually caused by either the pH or disinfectant level being outside of the recommended range. If the free chlorine level is too low, or the combined chlorines too high, this can cause irritation and is unpleasant for bathers.

Key parameters to check: pH, chlorine.


  • Measure pH levels to ensure they are within the recommended range (ideally 7.2-7.4). If the pH is outside of this range, then adjust.
  • Measure free, combined, and total chlorine levels. If any of the chlorine values are outside of the recommended range (free chlorine residual of 1.0 mg/L, combined chlorine less than half of the free chlorine and never more than 1 mg/L), then adjust.

8. Problems with Scaling or Corrosion of Pool Fixtures and Fittings

If there is scaling or corrosion on pool fixtures and fittings this is likely due to the water not being in balance.

Key parameters to check: Water balance.


  • Carry out a full water balance test to identify the issue.
  • Adjust the water chemistry parameters as necessary.

Most pool water issues are due to imbalance of chemical parameters in the pool. Palintest’s Lumiso Pooltest Expert offers tests for all key and troubleshooting parameters required to diagnose and treat pool water issues, as well as for day-to-day monitoring. With on-screen instructions included for every test, and user interface customisability including the option to add notes, labels, and users to tests, Lumiso Pooltest Expert makes pool and spa water testing intuitive, quick, and simple.

Following a pool water issue such as one of those listed above, recording testing and resolution steps is extremely important. Lumiso Pooltest Expert also makes compliance easy through automatic results logging and easy export through Palintest’s new data management platform, Palintest Connect. To find out more about this brand-new pool testing photometer, please contact the team here.

Pool chemistry limits and recommendations in this article are collated based on industry best practice. We would always recommend you seek advice on the local regulations from your local advisory board. For further information on pool chemistry, download our pool chemistry guide.

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