Oh! A red-eared slider. Cool, I have good news and bad news.
Good news is, you probably don’t need to heat the water as long as it’s room-temperature. They live in all sorts of places, and low 70’s is fine for them.
Bad news is, they need a ton of space because they tend to get huge. A healthy adult RES is going to be like 10 inches long and need either a way bigger aquarium than you probably want, or a pond. Part of it is for the exercise, but more important is the fact that they pee in their water, and drink it. The more water you have, the better the pee:water ratio is for your turtle. A strong filter for the water is important too. It shouldn’t smell bad if you are doing it right. I can give tips on filtration if you like.
My first turtle was a red eared slider, I know a lot about them. They are very hardy, but very misunderstood. Very good turtle for a starting turtle-keeper provided you have the space for them.
Some stuff for them applies to all aquatic turtles. the main differences between aquatic turtles is how much land space you need, how carnivorous they are, and how well they get along with other turtles.
You can keep her in a couple feet of water easily as long as you have things near the surface that she can cling to to rest, and one area that she can completely climb out of the water to dry her shell. If she’s not used to that much water, start with a water depth shallow enough that she can stand on her hind legs and stick her head out, then gradually increase it each day- it may take her a little time to remember how to deal with deep water if she hasn’t had it for a while, but RES are extremely good swimmers by nature.
Also, RES are aggressive. Don’t put them in an aquarium with any other animal unless you are ok with them trying to kill it. This includes other turtles. They are often ok with turtles of their own species, but not always, and sometimes a bigger one will harass or kill a much smaller one.
Here is some more info from a source I trust:
austinsturtlepage.com/Care/c … slider.htm