My cats have pretty bad tummys still. I have been using Bob Martin which clumps really well but doesnt have good odour control at all and tracks badly. I have just change to Oko plus but find that it doesn't clump that well and I end up with loads of little clumps spread across the litter tray which makes cleaning impossible. Can anyone recommend a great litter for runny tummies?? Not too expensive as I'm having to empty the tray at least twice a week because it gets in such a mess!