Can a Turtle Tank Be Too Deep?

If you’re the proud owner of a turtle, it’s likely that you spend quite a bit of time ensuring they have the best possible environment to live in. From selecting the right size tank to making sure your turtle has the right type and amount of food, there are many things to take into consideration. Many turtle owners have questions regarding the specifics of setting up the best tank for their pets, including whether a turtle’s tank can be too deep. 

Can a turtle tank be too deep? As long as your turtle can easily swim to the surface and reach the basking area, a deep tank is okay. As a general rule, water should be 2-3x as deep as your pet’s shell is long. Be sure to monitor your turtle to ensure it doesn’t have trouble reaching the basking area or water’s surface.  

Now that you know the proper amount of water to add to your turtle’s tank, it is essential to learn about other elements that create an ideal environment for your pet to thrive. Not only is having the proper water depth essential but ensuring water health and tank safety as a whole is also important. 

How to Fill Your Turtle’s Tank With Water

If you are raising a turtle from the hatchling stage, you will want to get a tank that your turtle can grow into as they age. However, when they are very small be sure to avoid overfilling your turtle’s tank.

Your pet turtle should be able to swim from the very bottom of the tank to the water’s surface easily, without running out of breath. As your turtle grows and their lung capacity expands, you can add more water to the tank. 

It is a good idea to add just a few inches of additional water at a time and to wait a few days before you add more. Watch your pet turtle during these few days to ensure that they are not struggling to reach the surface, the basking area, or the rest spots that you add throughout the tank.

If your turtle appears to handle the additional water without a problem in those few days, go ahead and add more. 

It’s important to remember that turtles are not originally domestic pets. Turtles naturally live in the wild, in large ponds and bodies of water. These turtles get along just fine when they are born in these significant bodies of water and should make it in your at-home tank as well as long as you set everything up properly.

Finding the Right Size Turtle Tank

Selecting the right size tank for your turtle is also important. If you are raising one turtle, a 15-gallon tank should do the trick depending on the specific species. If you are raising two turtles in the same tank you will require a 20-gallon tank, minimum. As your turtle grows, you may need to buy a bigger tank to accommodate more water.

A good point of reference to go by is that for every inch your turtle is long you should have at least ten gallons of water in the tank. While it’s unlikely that you can make your turtle’s tank too deep, it certainly is possible for it to be too shallow.

Keep in mind that your tank will need to accommodate the proper amount of water as well as the basking platform for your pet, along with any decorations you choose to add as well. What this means is that a 20 gallon tank will not hold a full 20 gallons of water. 

To select the proper size tank, take the amount of water you will need to add and then select a capacity that is at least 1/3 greater than that amount. This way your pet turtle will have plenty of room to swim, eat, and rest without crowding. 

Adding Additional Resting Places

In addition to making sure your pet turtle can reach the basking area without stressing out its lungs, you can help ensure its safety by adding additional resting places in the tank. You can add plants or rocks, whether real or fake depending on the set-up of your aquatic tank.

This may be particularly helpful to your pet turtle if your basking area is above the tank or if your turtle is very young and small. As your pet turtle gets older and can swim more easily across the entire span of the tank and reach the surface, they may not require as many additional resting places. 

Picking the Right Tank Substrate

Not only will you need to add the proper amount of water to your turtle’s tank, as well as a basking platform and additional rest spots for your pet, but you will need to add a tank substrate as well.

A tank substrate is what covers the bottom of the tank, often small rocks or smooth gravel. When selecting the size of your pet turtle’s tank, it is imperative that you account for the amount of substrate you will be adding to the bottom as this also detracts from the amount of water that fills the tank. 

 Examples of good tank substrates include:

  •     Large, flat rocks
  •     Smooth, tiny gravel
  •     Fine sand
  •     Fluorite
  •     Crushed coral
  •     Aquarium gravel

Some turtle owners choose not to add a substrate to the bottom of their tanks at all. This is a personal choice, and a substrate is not necessary unless you plan on using real plants in your aquarium.

Many people choose to go without a substrate as a smooth glass surface is easier to clean. However, others like the way that substrates such as crushed coral or fluorite look in the tank and add them for aesthetic reasons. 

When Water Is Too Shallow?

Now that you know that it is unlikely that the water in your turtle’s tank can be too deep, and how to measure it appropriately, it’s important to know whether or not the water can be too shallow. Not having enough water in your turtle’s tank can have a negative impact on the health of your pet. 

 When the water in a turtle’s tank is too shallow, it poses several risks. First, the water can get very dirty in a short amount of time from your pet’s fecal matter and bits of food. The smaller your tank is, and the less water it holds, the more challenging it will be to keep clean. Dirty water presents the possibility of harmful algae overgrowth, which can make your turtle sick.

 Additionally, while it is rare that water in a turtle’s tank can be too deep, if it is too shallow it may be a danger for your pet. For example, if your turtle accidentally winds up on their back, shell down, they will need to be able to correct themselves. If the water is too shallow, they may not be able to do so. 

Does Species Matter?

Not all turtles prefer the same habitat and it’s essential to recognize that what species of turtle you get as a pet does matter when determining how deep your tank should be. For example, there are some species of turtles that love to be underwater, such as loggerhead turtles, and they may stay under the surface for hours at a time completely undisturbed.

This is also the case for painted turtles and red-eared sliders, which can stay under the surface of the water for extended periods of time without issue. These species of turtles are known as aquatic turtles.

Still, there are some species that prefer to spend more of their time either basking or in very shallow water. These species include box turtles, reeves turtles, and mud turtles. These turtles may have a difficult time swimming from the bottom of a tank up to the surface if the tank is too deep, as they are known to get tired much more quickly. 


When asking whether a turtle tank can be too deep, it is important to recognize that turtles are, for the most part, water creatures with a great ability to swim. While you should start off with less water in your tank if you are raising a hatchling, once your turtle is fully grown it is not likely that you can add too much water to their living space.

Water can, however, be too shallow and pose health and danger risks to your pet.

The key is to evaluate your turtle’s tank based on the species of turtle you own, how old it is as well as its size, along with the individual traits and behaviors your pet displays. Additionally, it is imperative that you add proper resting spots and accessories to help your turtle climb to the surface of the tank if necessary.

Now that you know all about turtle tanks, the proper depth, the right amount of water, and other necessary elements to creating the ideal environment for your pet turtle to thrive, go on and create the space of your turtle’s dreams!


I’m Devin Nunn, an average joe that just so happens to have a deep love and passion for everything to do with reptiles. Because taking care of them for the vast majority of my life wasn’t fulfilling enough, I decided to begin educating others about them through my articles. read more...