I have a question for all of you in snow/freezing land. How deep is your tub for water in the winter? If it's relatively deep, how do you make sure they can get out easily? I have this black rubber tub (15 gals 9 3/4 inches high). I have one goofy duck who pretty much lives in it (she thinks it's her personal pond). This morning I noticed that her foot kept slipping when she was trying to get out. I have two large rocks in the bottom hoping that would give enough height for her to be able to step up. I'm thinking I might need to add more rocks. There's a ramp on the outside, but that's not helping inside. The mouth is not wide enough for a ramp, you can fit two full grown ducks in it barely. Any thoughts/ideas?