The type of sensors installed OEM by the manufacturers are fairly reliable... until you use the tanks the first time. We just judge by time and usage as to when to dump. Every now and then I'll get really motivated and put 1/3 tank of fresh water in the black tank (ours has a built-in tank washer that I use to do this) and add 1/2 cup of dishwashing detergent and 1/2 cup of borax crystals before we hit the road. If the day's trip includes a bombed-out interstate or some back roads in New Mexico or Louisiana, even better! If this process cleans the sensors, they may stay that way for one or two dump cycles. Then it's back to judging by time and use... (Oh, no! It just occurred to me - we're having MORryde independent suspension installed in a few weeks. The ride will smooth out so much I probably won't get the washing machine agitation in the tanks any more.)
Rob
