Throughout pumping, maintain steady vacuum, prevent tank wall damage, separate heavy solids with agitation

https://iris-wiki.win/index.php/Sewage-disposal_Tank_Pumping_as_well_as_Servicing:_A_Home_owner%27s_Step-by-Step_Resource

During pumping, maintain constant vacuum, avoid tank wall damage, break up heavy solids with agitation, and never ever go into the tank; lethal gases require strict confined-space safety procedures.