First off, mice and birds(fur and feathers) have nothing to do with impactions. Impactions are caused by many other enviornmental conditions or desease.
The most common enviornmental condition is dehydration. The most common cause of dehydration is open/screen tops. I discribed this many years ago, as a beef jerky machine. That is, you use a heat source(lamp) to heat a spot(hot spot) this in turn heats the air, the air quickly rises. As it raises, it draws as must moisture as it can carry. It will take this moisture from the substrate, water bowl, and the bag of water you call a monitor. The hot humid air is rapidly replaced by cooler dry air from the room(most rooms are dry) The process is continous.
The reason I call this the "jerky" condition is, this is exactly how jerky is made. Also, you can test your cage by making jerky. If you place sliced meat in the cage and it drys out(becomes jerky) instead of rotting, then the cage has too much air movement.
Remember, monitors are salamanders with a tiny bit thicker skin, this thicker skin is to slow down dehydration. It does not and cannot prevent it. In nature, monitors and most reptiles daily activity is primarily controlled by the gaining and loss of moisture. Behaviorally they do every thing they can to not lose bodily moisture.
All the soaking and baths(holy moly, what has this world come to) will not solve this problem. It simply changes its direction, now instead of impactions, you can have some lovely uric acid crystals forming in the kidneys and related ductwork.
Please look into why your monitor is dehydrated, the above, is only the most common cause, not the only cause. Good luck with your monitor, FR
