3. Do you know how to clean the filter sand regularly ?

After about 5~10days ,or when the reading of the pressure gauge on the pump side of the filter has increased by about 0.2bars since the last backwash , backwash the filter as follows: 1. Stop the pump 2.Close the valves on the suction and return lines. 3.Open the cover of the pump and empty the filter gasket . 4.Refit the cover 5.Open the valve to the drain outlet 6.Turn the lever to BACKWASH 7. Open the valves to the suction and return lines. 8.Start the pump .Rinse the filter for about 1 to 2 minutes until the water in the sight glass is clear . NOTE : Any electric heater must be off . 9. Stop the pump 10. Turn the lever to RINSE , start the pump and rinse for about 15~30 seconds. Stop the pump and turn the lever to FILTER . This is the normal operating position . 11. Close the drain outlet valve and start the pump . Switch on the electric heater if any .