Red-Eared Slider Tank Size Requirements

red eared slider turtle tank decor ideas
Contributed by Jace Vang

Let’s get one thing straight here: There’s a common misconception that red-eared slider tank size limits how large the turtle grows. I’m not sure how that myth started, but turtle size is not — and has never been — limited by the size of its enclosure. So, housing a turtle in a tiny tank in an effort to keep it small forever will inevitably fail, and in the process you will be providing woefully inadequate care for your pet.

In the wild, red-eared slider enclosures don’t exist. Instead they have free access to entire ponds and other bodies of water, traversing relatively large distances in their daily hunt for food. These territories are so large that to perfectly replicate one in captivity is quite unrealistic for most reptile keepers. And unfortunately, there is no one perfect formulate for determining the “perfect” enclosure size for captive reptiles. However, we can look at established minimum enclosure size standards, and then commit to provide larger if at all possible.

Among turtle keepers, the generally accepted minimum for housing a turtle is to offer 10 gallons/38 liters of water per inch of shell length. For example, a 4” turtle would need 40 gallons/150 liters of water to swim in, and a 12” turtle would need 120 gallons/450 liters. The depth of the water should also be at least the length of the turtle’s shell, preferably deeper if you can provide it. For clarification, that’s the minimum amount of water that is needed for housing a red-eared slider properly. Land area is a separate requirement, as red-eared sliders spend most of their time in the water.

Remember: bigger is ALWAYS better! And with a reptile as active as a red-eared slider, you can be sure that the extra space will be appreciated.

So what size of enclosure should you get to start out? To save you money in the long run, it’s best to buy an adult-sized enclosure right off the bat, even if your new pet red eared slider is just 4” long. Since most red-eared sliders top out between 8-11”, ReptiFiles recommends 100 US gallons (379 liters) as the minimum acceptable red-eared slider tank size.

The above “minimum” may seem enormous to you, and possibly even unreasonable compared to examples you’ve already seen. However, keep in mind that red-eared sliders are among the most abused and underhoused reptiles in the hobby! One of the many reasons for this is the fact that they are chronically kept in enclosures that are far too small for them. Just because you see someone online keeping their pet red-eared slider in a smaller enclosure and asserting that the animal is “just fine” does not mean that what they’re doing is anywhere close to best practice. 

NOTE — Water is HEAVY! Even a bare minimum, 100 gallon/379 liter glass aquarium with nothing else in it weighs ~831 lbs (377 kg). Take this into consideration when planning where to set up the turtle’s enclosure. Make sure the floor can support the setup’s weight — the ground floor or basement of your home typically works best.

What type of enclosure do you need for a red-eared slider?

Red-eared sliders and other pond sliders are semiaquatic, or they spend time both on land and in water. And to be specific to pond sliders, they spend most of their lives in water, with regular but brief excursions out of the water to dry off and bask.

Therefore, a red-eared slider enclosure must be able to accommodate both of these needs, providing a large amount of water and a relatively small amount of land area.

GOOD: Glass Aquarium

Some people use glass aquariums to house their turtle indoors. Glass is very attractive, and convenient since it provides a waterproof enclosure that is ready to be used immediately. But it’s also heavy and expensive. While there are aquariums large enough to meet the minimum housing requirement for a pond slider, these aquariums can be prohibitively expensive, difficult to access, and will require modification to provide an appropriate basking area.

For human convenience, you may also wish to purchase a tank stand to go with your red eared slider tank. Tank stands are strong enough to support the weight of all of that water, plus they’re attractive and bring the enclosure up to eye level. Tank stands can be pricey, so you may wish to build one yourself.

If you want to stick to the 100 gallon minimum, then I have some bad news for you: 100 gallons is actually a not very common aquarium size, so because it’s rare, it’s relatively more expensive. Rather than stepping down to the more common 90 gallon size and potentially sacrificing your pet’s quality of life for convenience, I recommend stepping up to 120-125 gallons instead. This size is more common, making it more reasonably priced, and your turtle gets more space in the process — it’s a win-win!

I have found that GlassCages.com seems to have the most accessible pricing for a standard 120 gallon, 48” x 24” x 25” aquarium (base price $580 USD as of  January 2021). Other sizes up to 500 gallons are also available for relatively low prices compared to other options I’ve observed on the market. GlassCages.com also offers reasonable-priced custom tank stands to go with their aquariums, which I recommend taking advantage of if you’re not inclined to build your own.

Other turtle aquarium options include the Aqueon and Marineland brands. Petsmart has a surprisingly good deal on a 125 gallon Aqueon LED Aquarium & Stand combo.

Whenever possible, it’s best to purchase your turtle’s aquarium in-person rather than ordering online, as you will save a lot of money by avoiding shipping costs.

BETTER: Custom Turtle Tank

Alternatively, you can pay someone to build a custom semiaquatic turtle enclosure for you. Custom enclosures can be wonderful. They’re expertly made, can be any size you want, and may boast neat features like built-in lighting and basking areas, 3D backgrounds, and connecting to your home’s plumbing system. Plus, there’s usually a significant emphasis on aesthetics, turning the enclosure into a piece of furniture or even living art that you’ll be more inclined to show off than hide.

Custom-made red-eared slider tanks can be ah-maz-ing. But keep in mind that higher quality means more expensive, so this would definitely be a major long-term investment in your red-eared slider’s husbandry.

Here’s where you can order custom turtle tanks:

BEST: Indoor/Outdoor Pond

Most red-eared slider owners opt for housing their pet in a pond of some kind, whether indoor or outdoor. Artificial ponds are easier to access and maintain, are generally less expensive, and can be just as beautiful as an aquarium (if not more so).

The opaque walls of a pond also help turtles feel more secure in their surroundings, and can help reduce or eliminate “pacing” behavior. In the wild, a basking turtle’s first response to danger is diving into the water to hide. In a glass aquarium, however, going underwater doesn’t offer that same sense of security, which can cause stress.

How do you create an indoor turtle pond?

There are several alternative materials you can use to create an indoor pond:

Whichever you choose, make sure its dimensions and capacity still meet the “10-gallons of water per inch” red-eared slider tank size rule. Also make sure that the material you are using is strong enough to hold water without leaching chemicals into it.

One important consideration to make as you plan your red-eared slider’s enclosure is location. Water doesn’t seem that heavy when it’s in a cup in your hand, or even a gallon jug, but when you put hundreds of gallons in one concentrated area, that weight can threaten your home’s structure. For this reason, it is best to set up your indoor pond on the lowest floor of your home where the weight can be supported by the home’s foundation. Otherwise you risk warping and possibly even breaking the floor!

Here are some examples of indoor ponds that others have built:

How do you create an outdoor turtle pond?

Depending on where you live, an outdoor pond may be a better option for housing your pet red-eared slider either for part of the year or year-round. Outdoor ponds are convenient because you can get heat and UVB “for free” from nature. It also tends to be easier to provide a spacious living space for your pet, since you don’t have to worry about weight and you don’t have to sacrifice any of your indoor space.

However, you can’t just dig a hole in your backyard, line it with a tarp, fill it with water, and plop your pet turtle in. Just like an indoor enclosure, you need to customize an outdoor pond to fit a red-eared slider’s specific needs, or else you risk your turtle becoming sick and possibly dying.

The good news here is that red-eared sliders are incredibly hardy. If you live in an area where they can be found in the wild, whether because they’re invasive or native, you can actually leave your red-eared slider out year-round with the right precautions. And even if you don’t, you can probably house them in an outdoor pond during the summer months, as long as you can provide an appropriate basking temperature.

Specific instructions on how to build an outdoor turtle pond are a little beyond our scope here at ReptiFiles, so here are a couple of resources that we recommend if you want to take this direction:

NOTE: Whenever you house a reptile outside, predators become a concern. Animals such as dogs, cats, raccoons, birds, opossums, and rats (as well as neighborhood children, although they’re not really “predators”) can invade your turtle pond and cause serious harm to your pet. So make sure to put a fence around your enclosure, and lay chicken wire over the top. Beware of fine netting, as this may filter solar UVB too much, and any gaps between fence slats should be too narrow for the turtle to fit through for escape. You’ll also want to dig your fencing deep into the ground as an additional precaution against escape.

outdoor turtle pond
Photo courtesy of Roman Muryn

Can red-eared sliders be housed together?

Pond sliders like red-eared sliders seem to get along in groups, as they’re frequently seen together in the wild or housed together in outdoor ponds. However, that doesn’t necessarily mean that they should be housed together as pets.

If you only have one turtle or are only planning on buying one, then that’s perfectly fine! In fact, many sources recommend housing red-eared sliders singly in order to maximize the likelihood of keeping them safe and unharmed. A red-eared slider can live happily by itself, and unlike humans or other obviously social animals, they don’t seem to need “friends”.

If you want to have a pond with multiple red-eared sliders, here are some rules to follow to reduce the likelihood of injuries, cannibalism, and other problems that can occur:

  • only house turtles of similar size together
  • supervise feeding sessions to make sure that each turtle is getting enough to eat
  • provide either an extra-large basking area or multiple basking spots (both heat and UVB)
  • add an extra 20 gallons of water per additional turtle, minimum

SUMMARY —

  • Red-eared sliders need a minimum of 10 gallons of water per 1” of shell length.
  • Standard rectangular glass aquariums are attractive and easy to acquire, but they will require lots of alteration.
  • Custom turtle tanks can be **amazing**, but they cost $$.
  • Waterland tubs are **amazing** AND they’re less expensive.
  • You can save more money by using a plastic stock tank or similar container.
  • Best case scenario: build your turtle a pond.
  • Don’t house multiple turtles together unless you have a big pond.