Step sludge and scum with a sludge judge to validate pumping need

https://wiki-club.win/index.php/Sewage-disposal_Tank_Emptying_Book_as_well_as_Ideal_Practices_for_Long-Term_System_Health_And_Wellness

Measure sludge and residue with a sludge judge to verify pumping need, then blend contents carefully to suspend solids so the vacuum truck removes both layers, avoiding obstructions and premature refilling.