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

https://fair-wiki.win/index.php/Specialist_Sewage-disposal_Tank_Maintenance_%26_Pumping:_Affordable_Service_Checklist

Step sludge and residue with a sludge judge to validate pumping need, then mix contents carefully to suspend solids so the vacuum truck gets rid of both layers, preventing clogs and premature refilling.