If your pool is currently hazy or milky blue, there are likely multiple reasons why…

50 Causes of Cloudy Pool Water

Pool Water Chemistry

  • Inconsistent chlorine levels, below 1.0 ppm
  • High combined chlorine levels, above 0.3 ppm
  • High pH levels, rising above 7.6
  • High alkalinity levels, above 150 ppm
  • High calcium levels, above 400 ppm
  • High cyanuric acid levels, above 100 ppm
  • Very high total dissolved solids, over 10000 ppm
  • Heavy use of calcium based pool shock
  • High levels of particulate matter, i.e. dead algae, pollen, dust
  • Adding more than one chemical to the pool at a time
  • High saturation index as pool water gets warmer
  • Using chlorine products in a Biguanide treated pool

Pool Water Contamination

  • Dead remains of previous algae blooms
  • Using low grade pool salt with impurities.
  • High levels of phosphates or nitrates
  • Heavy use of Quaternary Ammonium algaecides
  • Dirty pool, lots of leaves, debris
  • Urine, Sweat, Fungus and bacteria from swimmers
  • Tanning oils, cosmetics and hair products
  • Run-off from nearby lawn or planters
  • Sap and pollen from overhanging trees

Equipment Problems

  • Pump impeller is clogged or broken
  • Pump not running long enough each day
  • Pump is too large for the pool filter
  • Pump is overheating and cycling on/off
  • 2-speed pump, operating only on low speed
  • Pump basket or skimmer baskets full of debris
  • Low water level, drawing air
  • Stuck skimmer weirs, drawing air
  • Air leak on pump, drawing air
  • Poor circulation in a large pool
  • Filter is too small for pool size or pump size
  • Filter is not being backwashed fully or properly
  • Filter cartridge not seated properly, or missing parts

Filter cartridge or filter sand needs replacement

  • DE filter is leaking DE powder into the pool
  • DE filter with too much or too little DE powder
  • DE filter grids are clogged with oil or minerals
  • Multiport valve is recirculating or bypassing filter
  • Suction or return valves are closed or clogged
  • Salt chlorinator cell needs cleaning
  • Salt chlorinator cell needs replacement
  • Salt level in pool is too low to salt cell
  • Tablet chlorinator is gummed up
  • Tablet chlorinator has an air lock

Other Problems…

  • Rough pool surface, not being brushed regularly
  • Fresh pool plaster (will dust-up for about 6 months)
  • Swimming pool paint dissolving, from low pH & alkalinity
  • Too many swimmers, over 1 per 50 sq ft of area
  • Dogs, ducks or other animals using the pool regularly
  • Cloudy pool water has many causes, and frequently more than one. Attack it methodically by checking for contaminants, ensuring your equipment is operating properly and the water chemistry is dead on, and your pool water clarity will return in no time!