I have 2 hatchling red ear sliders and have a small tank but i'm in the process of building a cement tank for them. I wanted to know if cement tank is safe for them and do I have to have water plants in it?
probably not, especially for hatching. they could get cuts on their nose and feet, and the tank could get too hot or cold and kill the turtle.
Cement will leach lye into the water; I highly recommend that you do not use cement for a turtle enclosure.