some questions about my white-face roborovski

Question
Hi,

I have 4 white-face robo. 2 males and 2 females.

Firstly, is a 4ft tank too big for them? Or the bigger the better?Is 1 wheel enough for them?

Secondly, its the 3rd day that i've bought them home. 3 of them are very active and they even run together in a wheel! but there is 1 of them which i'm not sure why, she seems to be sleeping all the way in some corner of the tank.
Is she sick? or could she be pregnant??

they are all around 5-6 weeks old. i bought them from a pet shop where all the hamsters are being kept together in a tank.

Answer
Hello, a four foot tank is big and the bigger the better!! However, even though it's fun watching three hamster get into a wheel and go up and down the wheel and get knocked off I would buy another one since you have some active hamsters that love the wheel. :-) The fourth dwarf hamster that you have, is she active in any way or is she just huddled in the side all day and not moving? She may be sick if she's not eating or drinking or active. The babies being 5-6 weeks old should be active. The one thing I would do is to seperate the boys from the girls if you don't want to have babies. I would take the less active hamster to a vet because she does seem sick.