here is my 40 breeder turtle tank. it has a common snapper, western painted, peninsula cooter, and 4 goldfish, everybody is 4". now before you tell me how horrible and stupid i am for having a snapper with anything, everyone only gets pellets, so they arent very used to going for live food. and he has been with very small turtles since he was a baby so he shouldnt see them as food. i have never seen any agression from him that wasnt directed at pellets. even when there is food in the water and another turtle puts their foot right in his face, he simply pulls away. i know i am running a risk here, but i still wanted to share my setup. and for the record i do not suggest mixing snappers with anything, this is something i am trying and so far have not had any problems. the filter is a whisper 5. they dont make it anymore, it takes 2 XL bio-bags and i think was rated for up to 100 gallons. i love whispers and suggest and use them for everything from fish, turtles, newts, frogs (ones where it is actually useful to have a filter). the lighting is a 160 watt powersun mercury vapor. it provides heat and UV. i feed about 7 types of pellets for variety and a truly complete diet. i dont use any live food because it can easily introduce parasites and disease.