Whatever the manual lists, and nothing else — rake and drum machines need firm, fast-clumping litter, while ScoopFree-type machines need crystals and jam on clumping clay.
The machine defines the litter, not your preference. Three families, three rules.
Rake and drum machines
They lift a clump, so the clump has to set fast and hold together. Fine-grained clumping clay does this best; a soft, slow-setting bargain bag is dragged through the bed and the machine gets blamed.
Crystal machines
The ScoopFree Ultra takes crystal litter only. Crystals absorb urine and dry solids rather than clumping, and clumping clay in one of these is the most reliable way to jam it.
Plant litters
Tofu clumps well and weighs far less, which matters if you carry the bag upstairs. PetPivot excludes plant litters entirely; PETKIT accepts tofu among its clumping types; several makers exclude tofu from warranty because the grains swell when wet.
The practical test
Buy the small bag first. A 4.5 kg (9.9 lb) bag tells you within a week whether the cat and the machine both accept it, and 10.8 kg (23.8 lb) of rejection is an expensive way to find out.
The questions owners ask
Is tofu litter safe for these machines?
Several accept it and several exclude it from warranty because the grains swell. Both are true at once: your manual decides, not a review.
Last reviewed 2026-08-17