[TAKPAK]

Hi Dave from Albany, OR. Terry here, from Hillsboro OR. Yep, as has been said, you've got two grey tanks, the company just lumps them together as a total capacity. And as mentioned, the fresh tank and the two grey tank monitors usually work fairly well. The black tank one though, is worthless. It gets stuff on it, and even flushing doesn't always remove everything. The "burp" method of telling when it's getting close works good. Also, if you listen close, you CAN tell by the noise of the flushing water about how full it's getting as well.

Safe travels.