i had 2 red-eared slider turtles, and i reccommend giving them a variety of food. a pellet only diet usually does not give them the full range of extra vitamins and minerals that turtles need, especially while they are young, and need extra calcium, and vitamin d to produce a hard shell. if they get soft-shell it can lead to many complications. lettuce is fine, i gave mine some, just keep it varied. you can also give them little shrimp or krill that the petstroe sells in the same containers as the pellets, they are probably lov=cated on the same shelf. turtles can eat friut, insects, mine loved potatoe peelings, lol. when they get bigger, you can even put live minnows in the tank, and they will hunt them! i thought it was pretty neat, anyhow. dont worry about them not eating pellets. turtles eat a lot of different things, you will learn how much they need by trial and error, and learn to only put as much as they want in the tank. too much food floating around can lead to dirtier water and more cleaning for you. good luck! let me know if youve got any other questions!