depending on how dirty it is, you should empty the box completely and replace the litter at least once a week. having said that, i wanted to see what could be done with what we had, a ‘work on a zero budget’ concept. note: does this sound familiar to anyone? we all wore big smiles for the wait that is almost over. the process will only take about 20 minutes. it is our job to make you, and keep you comfortable and stress free. the worst feedback you can get is "average, so-so, 5 out of 10..." - how does that help? 