Thanks, both of you, for your helpful advice! I'm going to stick with using the sand (and yes, I know not to use the dust). I assume it's okay to put it in one of the corners of the cage to begin with, but move it to the hamster's preferred location if it chooses a different pee spot? And then I would put some of the pee'd substrate in it for encouragement, so to speak.
I am so determined to make fewer mistakes this time! Not that I made so many before, but using that former litter was not a good choice, and I know I moved a little too fast on taming (didn't give her enough time to settle in, and got a few well-deserved bites in the process!), and I'm sure I went overboard on treating her with sunflower seeds and pecans (hard not to do when she obviously enjoyed them so much!). But I realize it's a learning process. I'm very much looking forward to this new adventure, second time around!
