Problem Possible Cause Check / Remedy
Algae growth. Sanitiser level low. Sunlight dissipating sanitiser. High pH reducing sanitiser effectiveness. Not using preventative Algaecide. Ensure sanitiser / cyanuric acid levels are adequate throughout the pool. Reduce pH to recommended range of 7.2 – 7.6, Use maintenance algaecide dose.
Calcium hardness too high / scale formation. Build-up of calcium salts. If mains water has a lower calcium level, dilute the pool. Add a monthly dose of Stain & Scale Inhibitor.
Calcium hardness too low / pool grouting soft or eroding. Soft mains water supply. Increase calcium hardness level to a minimum of 200ppm.
Cloudy water. Build-up of swimmer pollution. Inadequate sanitiser levels. Cyanuric acid too high. Ineffective filtration. Water not ‘balanced’ correctly. Check sanitiser levels and if necessary shock dose the pool. Dilute to reduce cyanuric acid levels. Filter media needs cleaning / changing. Check water balance and adjust if required.
Chlorine level low / difficult to maintain. Lack of sanitiser / cynauric acid. High bather load / prolonged hot weather. Increase sanitiser dose and if necessary adjust cyanuric acid levels. More frequent shock dosing may be required.
Chlorine reading is zero using test kit despite chemical additions. Chlorine level may be too high causing test reagents to bleach. Chlorine demand (very high build-up of pollutants). Allow sanitiser level to drop naturally / lower using Chlorine Reducer or dilute by partially draining and refilling. Continue to shock dose pool water if over-chlorination is not the cause.
Chlorine level is high Over chlorination Allow sanitiser level to drop naturally, lower using Chlorine Reducer or dilute by partially draining & refilling.
Green staining Copper in pool water precipitating Test copper level. Check water balance and adjust if necessary. Add an initial dose of Stain & Scale Inhibitor. For sand filters, also use Aquasparkle Tabs or Flockfix Cartridges to aid with copper removal.
pH level high High pH of mains water. Alkaline shock treatment being used. Regular doses