Measure sludge and scum with a sludge judge to verify pumping requirement

https://wiki-tonic.win/index.php/Picking_a_Specialist_for_Sewage-disposal_Tank_Pumping_and_Cleaning_on_a_Budget_plan

Step sludge and scum with a sludge judge to verify pumping requirement, then mix contents carefully to suspend solids so the vacuum truck gets rid of both layers, avoiding clogs and premature refilling.