I found 1 of my hatchlings floating in the water this morning.I noticed that it had been staying out of the water the past 3 days. It probably died the night before after a cool front came thru. Then about 1pm. i noticed another laying on it's carapace on the bottom of the tank. As i retrieved it there was hardly any sign of life. After putting it in a empty tank it started moving ever so slowly. After an hour it was walking sluggishly. I put all 4 remaining ones in peat moss to night. Two things i've also noticed that their shells have gotten white-ish lately and their plastron has sunk in a little. I feed them daily and they are kept outdoors and are in about 10 inches of water and have a large basking turtle cliff w/filter. Please help!!!