soobie is exactly right. if you think she might be laying soon, lower the water level a couple of inches. this will encourage her to lay, and also discourage her from going exploring. i had a female brig who ended up holed up in her shell behind the tank for a couple days because she went looking for a place to lay, and fell behind the tank stand, where i couldn't find her. she recovered, fortunately, but it's always a good idea to provide a proper place for females to lay their clutches.