Pyrolox / sand filter with 2000 mm tank diameter. I fill the tank with 420 kg of quartz 2-4 mm on base. After that I put, in the succesive layer, 2360 kg of quartz 0.8-2 mm and 2120 kg pyrolox 8x20.
Work condition is: filtering flow is 40 mc/h, backwash flow is 192 mc/h, backwash daily with 30 min duration.
Water contain 0.385 mg/l manganesse and 0.08 mg/l iron. pH is arround the 7.0.
I put the filter in service and the concentration of manganesse in the filtered water not decrease below 0.130 mg/l.
Please help me with a advice, because I don't know is happen and where I wrong.
Thank in advance.