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

https://wiki-spirit.win/index.php/Septic_Tank_Pumping_and_Installation:_Cost-efficient_Solutions_You_Can_Trust

Measure sludge and scum with a sludge judge to confirm pumping need, then mix contents gently to suspend solids so the vacuum truck removes both layers, avoiding clogs and early refilling.