Ok, something I haven't even thought of......we have only used our camper once, just a shake down, and it was only for a few days.
We did not have sewage at our site, but after the trip, went to dump station to empty tank.

We are going for a week this coming Monday and will have sewage at our site. Do we leave the tank open to flow as we use it, or keep it shut and empty now and again?

I am embarrassed to ask, but I really just don't know.
Thanks