I flush when ever I can, which helps a bunch. Flushing not always an option so I put about one cup of dry water softener, one gallon of water and a few drops of dawn dish soap in to a bucket and stir well and then put that mixture down each tank plus a bag of ice and then run the camper around the block a few times and then drain. Then add that mixture again to each tank and let stand until the next time you use your unit. Helps clean the sensors and also helps with the smell! Been doing this for years and have never had a problem!