Red eared sliders spend 75% of their lives in water, which means you need to ensure the tank you choose can reflect this optimal habitat. But that's not all...
General Tank or Tub Guidelines
As noted above, if you have or desire to raise a red eared slider, you need to be aware of the fact these animals thrive in water.
In fact, the typical red eared slider will live around two-thirds of his or her life swimming, floating, eating and sleeping in water. The reminder of his or her time is usually spent basking in a warm spot somewhere.
Thus, it is crucial that the habitat you build for him or her mimic this split. Time and time again I have seen photos of friends and family members' sliders, and the poor thing is trapped in an aquarium that is too small, or isn't given any water in which to freely swim.
This begs the questions, what is the minimum size tank that you need? What is the best tank or set-up for my red eared slider?
Let's quickly tackle the first question. Tank and water size.
The rule is simple.
Your tank or aquarium size should be at least 10 gallons per carapace (shell) length. Thus, if your slider is 6 inches, you should aim for a minimum 60 gallon tank.
In my opinion, it's best to simply get the biggest tank you can afford as soon as possible, even if your turtle is still a hatchling. It doesn't take long for sliders to grow to their full-size of around 8-10 inches.
That means you should be looking at bigger tanks, around 80-100 gallons. Can you get a smaller tank? Yes, a 55 gallon will do, and it's certainly better than a 25 gallon. But it's not optimal.
If you are looking for a good, solid tank or a tub rather than building your own set-up, here are a few good choices.
Rubbermaid Stock Tanks
Rubbermaid stock tanks are a good option if you are looking more for function over form. If aesthetics aren't particularly important to you, and you simply want something comfortable for the turtles, and easy for you to keep clean.
They come in a variety of sizes: 50, 70, 100, 150 and 300 gallons (although I would probably not opt for the 50 gallon simply because it is not deep enough, at around 12 inches).
The build quality is very good. These are thick, tough rubbermaid tubs which are built to last. They are built for human bathing and commercial use, so they will not break easy.
Another pragmatic feature of these tubs is the conveniently placed oversized drain plug, which lets you quickly drain water for changes and cleanings.
There are a few drawbacks to tubs like these.
Firstly, they aren't exactly eye-pleasing! If you are thinking of placing your tank or aquarium in an area of your house which often receives guests, such as your living room, it's probably going to be a bit of an eye-sore. These tubs are generally better suited for basements or a place away from the general area of your house.
Secondly, you will need to do a little bit more work in terms of outfitting the tub with all the necessary gear your slider needs; such as a water heater, filter, UV lamp and basking area.
In particularly, the basking area might be a problematic for you if you aren't at all inclined to rig up or build things yourself, as you are generally going to be limited to a floating type of dock that you will need to create yourself.
A Large Glass Tank
Advantages of a glass tank:
Glass tanks are a good option if you are primarily looking for something more pleasing to look at. Form, rather than function, takes priority with these.
With traditional glass tanks, your options are more plentiful. Besides coming in a lot more sizes, literally from a single gallon all the way up to 400+, you've got more options with regard to shape, as well.
Besides a good looking tank set-up being absolutely amazing to look at, there is an added benefit; usually it is a bit easier to hook-up equipment in these types of tanks.
Most aquarium equipment: filters, water heaters and more, are built with these types of tanks in mind. A good example of this is the Turtle Topper, which is a snap to install on a traditional rectangular tank, but on anything else, you would have to do a bit of amending.
With every advantage comes a disadvantage however, and with these kinds of tanks, there is a big one; price.
The bigger your tank, the more you are going to shell out in the way of big bucks. These tanks easily cost hundreds of dollars, with some going well over $1,000. If you are dead-set on getting a tank but a little cash-strapped I would suggest checking out second-hand goods websites such as Craigslist to see if anyone is selling one for a decent price. You can usually get them quite a bit cheaper that way. Otherwise, I have used FishTanksDirect in the past and have been pleased (but be note that many of their tanks are pricy).
The other big disadvantage with these tanks is their propensity to break somewhat easily. Now, when they are all set-up, in a stable, good location they are quite reliable and safe. It's when you are moving it that they can be easily liable to break. I've had two different tanks break on me when I moved. It's not a fun experience!
Overall, the choice should be rather simple here: