[Albert the Dwarf Hamster]

Hello everyone, I need some advice. I adopted a Dwarf Russian Hamster over a month ago. He is now about 6 months old and his name is Albert. To begin with Albert used one corner of his cage to pee but has now decided to stop doing that. Albert likes to dig his own burrow system bed, food storage and toilet. Albert gets very angry if go anywhere near his burrow system so I can't clean his toilet. To stop Albert getting stressed and angry I've only been cleaning out his wee/toilet once a week. I have to put Albert in his pet carrier to complete this task which Albert is happy with. Albert's pee/toilet doesn't smell. But I'm worried Albert might become ill because I'm only cleaning out his pee/toilet once a week.