Bahco
I have a middle aged big fat puss Purdy,
who doesnt go out an she uses a litter tray ,
I find the best option is about 2" of litter in a high sided tray
the odourless kind from pets world is great for masking the pee smell an any poo is scooped up after she has been into a carrier an in the rubbish ...
when the litter is starting to whiff another inch of litter an I change the tray every 2 weeks ...
another good thing is one of those glass air fesheners placed near the tray ...
I lost 2 cats too illness awhile ago an it really tore me apart ...
btw forgot to say , Oxyclean crystals are a REAL marvel , but test on a bit of the carpet before you start using on a big piece of carpet , they have a neutralising smell too when dry , I used loads of it while my 2 cats were very ill