I don't want to be a dink here,but I think the origonal poster may have trouble understanding what we are tellingher, which is that she needs a MUCH bigger tank.
WHY you ask yourself?
Because 4 turtles in a little tank makes for one big turtle toilet.Could I exist in a landfill? Probobly.Would I like it?Probobly not.Even if you clean the tank every day, then that is really bad for the turtles because it kills off all the good bacteria that keeps the tank healthy.
Also, could I live permanently in my dorm room with 3 other people? Yes.WOuld I enjoy it? No. Especially if it was in a landfill.This is what you are doing to your turtles.If your RES is 4-5 inches long, there is no way it is full grown. Give us a shout out in 3 years and let us know how big he is.They get up to 10-12 inches as full grown adults.
In most cases, owning a pet is a choice.If you have 3 turtles, it is your responsibility to make sure their needs are met.That means investing in the proper size equipment to care for them and doing your homework as to what that entails. Yes, they are cute to look at and fun to watch, but cheap and low maintainance they are not.
Austin's turtle page and Kingsnake have pretty good care sheets that will confirm this is not a conspiracy theory against you getting another turtle, as they were started years before you got them.
Check out other set ups to see what other people have and maybe it will give you some good ideas.Good luck with your turtles, and check out the care sheets.
...Anne
1 RES JFK
1 Ankle biter 18 months