How large is your cage and how often do you change the bedding? I've found that different guinea pigs leave different odors in the cage... possibly due to scent marking... and might require more frequent washing. My fleece pads have uhaul pads in the middle and I use a single layer of uhaul pads underneath. I rarely ever go past 3 days before I change my fleece. They live in my dining room so I'm very particular about any odor. I have one cage that needs to be changed more often than my others. I make sure I always use the large load and heavy duty cycle when I wash and add one cup of vinegar and my regular laundry detergent. I loosely load the washer, don't overfill. You can stop the cycle and allow it to soak. My fleece pads always come out smelling fresh and clean, with no odor. I dry on the high/cotton setting.