My brother gave me 4 red ear slider turtles with about 5 to 6 inch diameter shells. I've had them in my 55 gallon fish tank for about 7 months. I want to put 2 of them in my pond which is about 16 to 20 foot in length and 8 foot wide at widest. I'm afraid they will rip liner while digging for food and hibernating. Does anybody have experience with turtles in a liner pond? I would like to know other peoples experience in general of having a turtle in pond ie., killing large fish, devasting plants etc. Hopefully I will hear positive experiences from people. I have epdm roof liner.