LEVOIT 4-Pack Filter for Superior 6000S

Iam very satisfied with the product 1 month i use it my humidifier works very good.However i have to mention that i dont use tap water i use double filter for salt and the other has permeability 0.2 μicro even though the filter has started to discoloration and to have a bad odoor.I can not understand why the manufacturer dont give precise directions how to clean changing every month the filters in this price is not acceptable. Nowhere i found that is washable levoit says not clean with water however in their picture down in the last photo with tiny letters says you can clean it with water.In conclusion like others have said already vinegar with water helps to clean the filter but i dont know how often and what damage is making to the filter.