base plate 6 for the grit chamber use and by altering the location of control plate 13 relative to deflection plate 15 in each case the adjustment could be made by providing slotted mounting apertures which would permit the horizontal sliding of control plate relative to base plate in each instance an engineer of ordinary skill will find any number of ways to accomplish this adjustment above the inlet device 12 15 there is established a roller system which on the one hand is induced by the deflected jet and on the other hand deflects the jet in the direction of the surface after leaving the guidance structure this folding up of the jet compensates after all for the somewhat higher density of the sludge water mixture as mentioned above the measure in particular the embodiment of fig5 provides a precisely predictable velocity profile at the end of the guidance structure 15 in the settling tank how flow takes place into the actual sedimentation chamber is consequently precisely known ideally the sludge water mixture leaves the inlet device horizontally at the boundary between the zone t separation zone and zone sp storage zone as is known the zone k clear water zone is situated above the.