Calgon & Dawn treatment for waste tank sensors issues works!

I recently had to replace the grey tank in my 30-year-old MH. The black and fresh tanks have the original sensor system which is foil tape at various intervals on the tank; it's still working fine. The new tank has the dreaded through-wall system, so I added the sensor reader to work with it.

Almost invariably after dumping it still reads at least 1/3; after several days it dries out and indicates empty. Ridiculous.

If it gets to be a real problem I'll try the Mopeka "sonar" sensor.