I replace about every week to two weeks depending on snake "output". If the snake goes, I replace it. I guess with small snakes, you could spot clean it, but I just replace the sheet with each cage cleaning. It's pretty absorbant as far as water spills and such, but with the larger snakes I'm keeping on it, nothing is going to make the pile disapear. It's a sheet paper product, so no loose particles or dust. I used carpet years ago and I finally gave up on it. It wasn't absorbant at all and liquids just seeped through it to sit at the bottom of the tank (yuck). Also, I really hated scrubbing that carpet and then waiting for it to dry thoroughly. For a really clean cage that is easy to clean, paper is the best product I've found.
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Lora