Hi, our cat will only use an indoor litter tray to do her business. She also never apparently learned to cover up her mess in the litter tray from her mother. She uses the tray and just leaves her business behind her - always has done. We've been using Oko Cats Best natural clumping litter, which was ok but it recently seems to have stopped clumping (!?!) and is also not v good at odour minimizing, although it is flushable, which is convenient. I clear the litter box at least once a day and clean the tray completely out once a week. We use plastic liners too. Can you please recommend a great, clumping, odour-minimising cat litter? All suggestions very gratefully received - getting a little tired of the constant low level smells.....