[Pebbles82]

Just to add when you put more substrate in - take the old out first and then spread it on top of the new so it smells familiar (after spot cleaning any pee). Although it takes a lot of substrate intially, you use less in the long run with spot cleaning and the cage base tends to stay clean and dry longer. Also it's best to leave her nest and hoards in tact unless they are pee;d on. Removing those can lead to bar chewing as well. If you ever do need to remove hoard that's pee'd on then put new food back in the same place and try and leave a bit of old clean hoard behind. The same with the nest - if it gets pee;d in then you'll need to remove it but try and leave a bit of the old nest behind that's dry. And keep topping up the toilet paper pile of nesting material so she can rebuild it.

Once they're settled they tend not to pee in the nest and it can be left alone for a really long time - they don't like it being messed with! The advantage of a house with a lift off roof is you don't need to take it out to check on her nest - you just take the roof off - so the nest doesn't fall apart. I wouldn't do that too often with a dwarf hamster though as it can scare them when the roof comes off and then they can abandon the nest. Best to check when she's out of the cage.