When the solid particles in a suspension are large and uniform in size, the pores of the filter cake are relatively open, and the filtrate passes through the filter cake at a relatively high velocity. Using coagulants to aggregate fine particles into larger clumps is beneficial for increasing the filtration speed.
For suspensions with fast-settling solid particles, using a filter press with top feeding of the filter media, aligning the filtration direction with gravity, allows coarse particles to settle first, reducing clogging of the filter media and filter cake. Incorporating coarser solid particles such as diatomaceous earth or expanded perlite into difficult-to-filter suspensions (such as colloids) can loosen the filter cake. When the filtrate has high viscosity, heating the suspension can reduce its viscosity. All these measures can accelerate the filtration speed.