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How to set up a semi-aquatic turtle tank

There is a wide range of semi-aquatic turtles. Some like red-eared sliders need a large aquarium of water and dry land (such as a basking platform). Others such as wood turtles need a terrarium (preferably outdoors) and a large bowl of water in which they can fully submerge.

Before you start on your project, you need to find out the needs of the turtle. In this article, we will look at how to set up a semi-aquatic turtle tank for a turtle that spends a substantial amount of time underwater. Some examples of semi-aquatic turtles include red-eared sliders, cooters, map turtles, and painted turtles.

How to set up a semi-aquatic turtle tank

Semi aquatic turtle tank setup

Getting started

The tank size needs to match the turtle’s size. A big turtle needs a big tank while a small turtle will thrive in a small tank. The right size ensures that the turtle feels secure and grows right. As a rule of thumb, the tank has to be able to hold 10 gallons of water for every inch of the turtle. So for a 6-inch turtle, you need to set up a 60-gallon tank.

The tank’s length should at least be about three times the length of the turtle, the width twice the turtle’s length, and the height twice or one and half times the turtle’s length. To ensure that the turtle doesn’t climb out, there should be 12 inches of space between the basking platform and the edge of the enclosure.

The glass of the turtle has to be thick enough to withstand the water pressure. Foe a semi-aquatic turtle tank, ideally the glass should be 0.4 inches thick at least. For any additional turtle, the tank needs to increase in size by half. So if you plan on housing two 6-inch turtles, you need to set up a 90-gallon tank.

The tank needs to be deeper than it is wide. This should allow for enough room for the turtle to flip itself upright if it gets turned upside down.

Some excellent turtle tank choices to start with include the SC Aquariums Starfire Glass Aquarium, a 150-gallon tank; and Tetra Aquarium Kit, a 55-gallon tank. Aquariums can be expensive but there are other alternatives. For instance, the 150-gallon Rubbermaid container is an excellent & affordable choice for two turtles.

Setting up the basking site

The basking site is where the semiaquatic turtle will spend most of its time out of water.  This spot should have a basking lamp and a heat lamp, both of which emulate the sun.

The basking platform needs to be large and easily accessible. When out of water, the turtle can then dry off before returning back into water. Expect the turtle to spend several hours here each day.

The land area should take up about 50-percent of the space in the tank. The area should be large enough for the turtle to move about comfortably.

There are several options available to you. Floating docks are available at most pet supply stores and they are a good choice as the platform adjusts to changes in water level. Commercially produced docks are affordable and easy to use.

You can also use rocks and logs to create basking platforms. Similarly, you can create landmasses that raises out of the water. If the landmass gloats, you can anchor it to the tank using silicone aquarium sealant (Aqueon Silicone Sealant).

You can either buy a turtle basking platform or you can build one. See our turtle dock purchase guide for choosing one and our diy basking platform guide for more.

The turtle should be able to access easily. Consider providing a ramp if the basking site doesn’t have a gentle slope that doesn’t go into the water. Creating a ramp isn’t difficult. Consider attaching a thick piece of plastic to the basking site. This can serve as a ramp. A sloping log can also serve as a ramp.

Installing lighting

Correct lighting is essential if the turtle to thrive. There are two sources of light – natural (sun) and artificial (UVA/UVB). 

However, glass/transparent plastic aquariums can heat up rapidly when exposed to direct sunlight, which will harm the turtle. As such, only turtles in wooden terrariums should be exposed to direct sunlight. For glass enclosures, artificial lighting is recommended. Install the light bulb over the enclosure with the help of a lamp fixture.

See our UVB guide for more on how to choose one and why they are so important.

Reptisun lamps (ReptiSun 10.0 T5 Lamp & Reptisun 10.0 bulb) are among the best on the market as they output the UVA/UVB light needed. These are quite popular and can be found in many pet shops and online.

Adjoin the bulb to the enclosure using a light fixture such as the REPTI ZOO Lamp Fixture.

Another option is the heat-producing UV lamps such as TEKIZOO UVA/UVB Sun Lamp. Many keepers use these to provide both warmth and lighting at the same time. While this seems rather convenient and a cheaper option, these are less favorable as they must be on if you wish to keep the enclosure warm.

If you wish to keep the enclosure warm during cold nights, the heat-producing UV lamps can’t provide that as they must be off during the night.

The light bulbs should be off for 8-12 hours during the night. This mirrors the natural cycle of the day.

Be sure to change the bulbs every six months, as they lose intensity over time. A UV meter can be used to check the quality of UV light the installed bulb produces.

Installing heating

Another important aspect of the tank is heating. Chelonians need the right temperature range to thrive and remain healthy. Heating needs differ from one species to another. You need to learn all you can about your pet’s needs which include heating.

To keep the water temperature within the right range, you may need to install a submersible heater such as the FREESEA Aquarium Heater. For most species, water temperature needs to be about 75 °F and mustn’t fall below 70 °F.

See our tank heating guide for more on choosing the right size for your application.

The submersible heater needs to have a thermostat to prevent the water temperature from getting too high or too low.

The enclosure also needs a basking lamp such as the Ceramic Heat Emitter. This lamp should be situated right above the basking spot. This lamp encourages the turtle to get off the water to bask. Basking dries the turtle and prevents infections. The basking spot needs to be at least 10 °F warmer than the water.

Use thermostats to regulate the heating devices within the enclosure.

Installing a filter

Turtles can be messy and the tank needs a filter. Filters keep the water clean and the turtles healthy. Because turtles are messy, the filter needs to be rated for more than what you have size wise.

There are several types of filters available but large canister filters are best for the enclosure. The higher capacity of such filters ensures that the filter doesn’t clog up. If you must use a submersible filter then choose one with the largest capacity. Canister filters may be more expensive but they worth the initial investment.

For a 50-gallon tank, I recommended the Penn Plax Canister Filter (marked for aquariums up to 100 gallons). For a larger tank, the  Penn Plax 1500 Canister Filter (marked for aquariums up to 200 gallons).

If you must go for a submersible filter then I recommend the Marineland Internal Canister Filter.

Even with a filter, you need to change the water in the tank every one to two weeks. This ensures that the water is clean enough. As already mentioned, turtles are messy and produce a lot of waste.

For more guidance see our filters for turtle tanks guide.

Adding substrate to the enclosure

Substrate has its benefits in the turtle’s tank. For starters, it is necessary if you have live plants in the enclosure. However, without live plants, they aren’t compulsory. Substrates make the tank more difficult to clean.

Additionally, bits of food can get stuck in between the substrates which leads to a dirtier and possibly smelly tank.

If you are still considering a substrate, options include sand, pebbles and flourites. 

Sand is most difficult to clean but turtles enjoy digging in it. If you go with gravel or rocks, just make sure they are large enough to where the turtle can’t swallow them and that there are no sharp edges.

Fluorites are ideal for aquatic plants as they provide the turtle with nutrients.

Adding accessories and decorations

Decorations may not be needed, but they help beautify the enclosure. Likewise, they also help make the turtle feel safe.

Some excellent accessories to include on the land are logs, rocks, and even plants. The turtle can hide in these. The objects on the basking site shouldn’t cluster the area and the turtle should have space to move in.

Both the plants in the water and on the land should be edible and non-toxic as the turtle may eat them.

The accessories and decorations shouldn’t have any sharp edges which can injure the turtle. Likewise, decorations need to be sterile. Store-bought decorations are sterile but objects picked from nature arent. Boil such objects to kill germs.

Decorations shouldn’t be tiny in size. This prevents the turtle from accidentally swallowing them.

Avoid any objects that the turtle can get stuck under.

Placement of equipment and decorations

The placement of the decorations and equipment is essential. Some equipment includes a submersible heater and a filter. Decorations include objects such as driftwood.

Place any foreign objects along the edges of the tank. This allows the occupants to swim freely.

Objects such as plants can be placed in the center of the turtle tank. All stiff and tall objects should be placed at the edge of the enclosure.

When you place objects within the enclosure, there shouldn’t be any tight spots for the turtle to get stuck in while moving.

Monitoring conditions within the tank

Small changes in conditions such as lighting, temperature, and humidity may not mean much, but with time these changes can stack up. To prevent the conditions from getting too bad, you need to monitor them carefully.

Tools such as UV meters, thermometers, and hygrometers can help you monitor conditions within the enclosure. Different species require different conditions so keep this in mind.

Filling the tank with water

There should be enough water in the enclosure for the turtle to swim. The water should be clean and dechlorinated. You can dechlorinate the water using a conditioner such as the Seachem Prime Fresh and Saltwater Conditioner

This conditioner also helps regulate pH level, ammonia, nitrite, and nitrate levels. The pH level of the water should be 6 to 8. The nitrate level should be below 40 ppm. The nitrite level should be below 0.5 ppm. The water should also contain no chlorine and ammonia.

The water level should be at least 5-6 inches depending on the turtle’s size. The water depth should be at least three-quarters of the turtle’s length.


  • Don’t use terrariums as these can leak. The glass may also crack under the water pressure.
  • Even small turtles can grow into large adults. Known the final size of the turtle when setting up the enclosure and plan accordingly.
  • Take the tank on a sturdy stand.
  • The tank can take up a lot of space, ensure you have the space for the enclosure.
  • Don’t place glass/plexiglass aquarium in direct sun. This can cause the enclosure to heat up pretty quickly.
  • Make sure that the decorations placed in the enclosure aren’t the types that can trap the turtle. Even semi-aquatic turtles can drown.

Semi Aquatic Turtle Tank Setup Video Walkthrough

Here is a classic video from TetraCare which walks through the process completely.


Semi-aquatic turtles are hardy creatures however, they do need an excellent enclosure to thrive. They require an aquatic set up with a large basking platform. Since they spend significant amounts of time out of water. Turtles such as map turtles, cooters, and sliders need such an enclosure.

Other semi-aquatic turtles such as box turtles require a more terrestrial enclosure but with a large water bowl to soak in. the turtle should be able to easily access the water bowl. Something to keep in mind is that the size of the enclosure is dependent on the size of the turtle.

The larger the turtle, the bigger the tank must be.

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