These pumps all operate on a vacume. You should :
1. place the pumpout hose connector onto the port on your vessel.
2. turn pump on
3. open valve on hose to allow sewage flow.
4. observe glass on hose to verify when tank is empty
5. place hose end in water to rinse the hose
6. close valve on hose
7. turn off pump
8: always fill the holding tank with water after pump out to rinse and then repeat first 7. steps.
ps. also put odor-loss in the head and flush with 1 gal of water to freshen tank, and you will have no odor.
Repeat at least once a month or sooner if required.