Thank you Mushrooms. Yeah, I can tell all of mine apart very easily. I tell people its like those parents who can tell the difference between their identical twins - when you're around your babies enough, you can see differences.

Oh, and I clean the water daily. It actually could go every two days before getting dirty, but I like to get a jump on it. Plus, that means if I forget a day, or go out of town its not as big of a deal.