Hello I have 3 turtles, Two Yellowbellied Sliders And One Red Eared Slider. I had them since they where about an Inch big, that so for about 3 months now. Lately there shell has developed thick white lines throughout the shell and around the edges. Im not sure if this is normal growing or something else. The shell seems to be hard, its not soft and it doesn't smell. They Live in a 55 gallon tank (soon to be 110 gallon) With a 4 stage 525GPH Canister filter, They also have a heat lamp, UV light, water heater, basking platform ( its alittle small I made them a tank topper with egg create but they didnt seem smart enough to use it yet.). They get fed once a day and it varies between Tetra ReptoTreat Suprema, Mazuri Aquatuc Turtle Diet, Fluker's Large Sun-Dried Red Shirmp, Super Worms, Live Crickets. Some times I Give them alittle bit of each of the first three. They seem very active mostly always swimming or digging in the rocks or sand, I even catch them moving around there plants. Here are some pictures of the turtles hope you can help.