The short answer
Most globe and open-top boxes are built for clumping litter: the sifting screen only separates waste that forms firm clumps. Crystal-tray boxes such as the PetSafe ScoopFree need silica crystals. A few, like the Furrykiddy robot box, state clumping, crystal and tofu. Non-clumping pellets don't work in sifting boxes at all.
What makers state
| Box | Maker-stated litter |
|---|---|
| Litter-Robot 4 | Any clumping litter |
| PETKIT PuraMax 2 | All kinds of clumping litter |
| PETLIBRO Luma | All clumping litters (clay, tofu, mixed) |
| PetCove PurrTek | Any clumping litter: clay, bentonite or tofu |
| Furrykiddy robot box | Clumping, crystal and tofu |
| PetSafe ScoopFree Crystal | Crystal litter (trays) |
| Pet Zone Smart Scoop | Clumping, crystal or pine |
Our compatibility checker lists the litters we cover that match each box's stated type.
Clumping litters that suit sifting boxes
- Firm clay clumps sift cleanly: Dr. Elsey’s Ultra or BoxiePro Bot, which BoxiePro designs for automatic cycles.
- Plant clumping litters are lighter, such as pidan tofu litter; check the box accepts tofu.
- Very fine or very light litters can slip through some screens; if waste smears, try a firmer clumping clay.
Crystal and pellet litters
Crystal-tray boxes use disposable trays or refills of silica such as ScoopFree Premium Crystal. Crystals don't clump, so clumping-only globes can't separate them.
Breeze-style pellets are for sifting-pan systems only and don't belong in a self-cleaning box.
Products mentioned
Questions readers ask
Can I use crystal litter in a Litter-Robot?
Whisker states any clumping litter; crystals don't clump, so they aren't a match.
Is tofu litter OK in a self-cleaning box?
Where the maker lists tofu or 'any clumping litter'. Keep the bed deep enough that it doesn't saturate.