The finest particles are difficult to filter away, so over time (despite the use of Cristal Clear and Chlorine) the water can still become turbid. You can solve this perfectly by letting the flocculation flocculate with Micro Floc or Floc Socks. These products stick the tiny particles of dirt together until they form flakes, but these flakes are retained by the filter.

- Micro Floc method:

 You add the liquid Micro Floc to the entrance of the skimmer. Then circulate the water. Afterwards filter the flakes away for 6 to 8 hours. Then stop the circulation pump. The finest flakes sink to the bottom of the pool at night. You can vacuum it up in the morning with a bottom vacuum cleaner, or leave it out along the bottom opening, or via the "drain" or "waste" function on the sand filter.

- Floc Socks method. Place a floculation sleeve in the skimmer for continuous floculation. Do not forget to rinse the cartridge filter afterwards. With a sand filter you have to keep the pressure gauge in mind. Too much pressure = dirty filter.