Red-Eared Slider Basking Requirements

red eared slider basking temperature

Current weather in red-eared slider habitat — Dallas, Texas, USA:

Red-Eared Slider Basking Temperature

Although they spend most of their time in the water, red-eared sliders still need to occasionally haul themselves out onto land to dry off and warm up. As cold-blooded animals (ectotherms), turtles rely on external sources of heat to “power” essential body processes such as digestion, metabolism, and immune function. The benefits of basking don’t stop there, however. Red-eared sliders bask for many reasons:

  • vitamin D3 synthesis
  • skin and shell health
  • shedding assistance
  • hormonal regulation
  • fighting off illness
  • wound healing
  • egg incubation
  • parasite management
  • the sheer pleasure of feeling the sun on their back

A red-eared slider’s basking platform temperatures should be as follows:

  • Surface temperature — 104°F (40°C)*
  • Basking air temperature — 85-90°F (30-32°C)

*Basking surface temperature recommendation provided by reptile heating expert Roman Muryn.

Use a digital probe thermometer with the probe on the basking area to measure approximate air temperature there. An infrared temperature gun can be reliably used to measure basking surface temperature when pointed at that area from the manufacturer’s recommended distance. This measurement should be taken from the basking spot a couple of hours after the basking rock has warmed up.

I like using an Exo Terra or Zoo Med digital thermometer and Etekcity 774 temp gun for measuring temperatures.

How do you heat the basking area?

Halogen heat bulbs are the best and most readily-accessible ways to replicate the way that the sun provides heat in nature, which is why they are the preferred method of reptile heating here at ReptiFiles. This is because halogen heat bulbs produce sun-like quantities of the most powerful infrared (heat) wavelengths: IR-A and IR-B. These wavelengths penetrate deeply into animal tissues, helping reptiles thermoregulate more effectively. IR-A in particular has been noted for its healing properties. You can learn more about the benefits of infrared here: Next Level Heating: Why Infrared Wavelengths Matter.

Here are some reliable bulb options to try, although keep in mind that the wattage needed to achieve correct basking temperatures can vary widely. So when in doubt, buy high, and if necessary, use a plug-in lamp dimmer like the Lutron Credenza to dim the bulb to the right temperature.

You will also need a lamp fixture. It should be dome-shaped and have a ceramic socket. I prefer using at least two lamps with deep domes to create a large basking area with more even heating where a reptile can heat its entire body at once. My current favorite heat lamp for this purpose is the Zoo Med Combo Deep Dome Dual Lamp Fixture.

Make sure to plug the lamp into a surge protector (not just a power strip) to help maximize your equipment’s lifespan.

Like placing the UVB lamp, it can be tricky to install a heat fixture over what is essentially an indoor pond. One of the most common methods of solving this problem is to simply hang the lamp(s) from the ceiling with light fixture chains to get it in the right place. The heat lamp should be the same distance from the basking platform as the UVB.

Red-Eared Slider Water Temperature

Because pond sliders are semi-aquatic, you need to create perfect conditions for the aquatic portion of their environment as well as the terrestrial. This involves making sure that the water temperature is within a safe, healthy range.

According to available scientific and empirical data, it seems that the acceptable range of water temperatures varies depending on the turtle’s size/life stage. Assuming optimal growth conditions, male pond sliders are typically considered “mature” at 3.5-4″ (9-10 cm) plastron length and females are typically “mature” between 6-7.5″ (15-19cm). Female yellow-bellied sliders seem to mature more slowly, reaching sexual maturity around 9″ (22-23 cm). (Source: Turtles of the United States and Canada, Second Edition, Ernest and Lovich, p.455)

  • Water temperature for hatchlings (<1 year old) — 78-82°F (24-29°C)
  • Water temperature for juveniles — 74-76°F (23-24°C)
  • Water temperature for adults — 70-88°F (21-31°C)

Adult sliders appear to tolerate a wider range of water temperatures than hatchlings, particularly colder water, which makes sense because they have larger bodies which are better able to retain heat gained from basking.

According to Ernst and Lovich: “When in water, hatchlings and juveniles normally occupy very shallow microhabitats with much aquatic vegetation” (p.448-450). This means that immature turtles are known to self-select for warmer water temps. The above optimal temperature recommendation for hatchlings comes from breeder data. Juvenile temperature recommendations are sourced from keepers experienced in maximizing the survival of pond sliders around 4″ long.

How to measure water temperature

You can measure the temperature of your turtle’s water with a digital probe aquarium thermometer (the Zacro LCD Digital Aquarium Thermometer is a reliable choice) to make sure it isn’t too cool or too warm. Because the turtle will mess with and potentially damage the probe if it’s just left in the water 24/7, only use the thermometer for occasional measurements by dipping the probe into the water, waiting for a reading, then removing it again. Regularly measuring the water temperature is important to make sure your water heater is functioning properly.

How do you heat the water?

The temperatures given above are simply provide acceptable minimums and maximums for indoor enclosures. If you need to heat the water, set the heater to the minimum temperature to help maintain a diverse temperature gradient. If your water routinely gets warmer than the maximum, you need to take measures to cool the water. Fortunately, water that is too warm without the cause being a water heater is rare.

To heat the water in an indoor turtle enclosure, you will need an aquarium water heater, but don’t just grab the first one you find — there are some important considerations to keep in mind when choosing a water heater for a turtle tank:

  • Encased in plastic to prevent direct contact
  • Rated for the amount of water in your enclosure
  • Automatic shutoff feature

Experienced turtle keepers recommend the following brands as the most reliable water heaters to use with turtles. Make sure to check that whichever heater you buy is rated for the maximum amount of water in your turtle’s enclosure. The following water heaters are all sufficiently rated to safely heat a large Waterland tub (200 gallons), but in the case of larger enclosures, you may need two weaker heaters placed on opposite sides of the enclosure.

Submersible water heaters which don’t come with their own protective plastic cover must be installed with one to prevent your turtle from getting accidentally burned! If you have a heater longer than 14″, you may need to piece a cover together yourself.

Water temperatures naturally increase during the day and decrease at night in pond sliders’ natural habitat. So it’s a good idea to turn the water heater off at night and then turn it back on in the morning, (unless you are raising a hatchling, as they are very sensitive to cold water). Personally I have found that it’s most convenient to automate this daily cycle with a smart plug. You can also use this to automate when your heat lamp and UVB lamp turn on/off.

Outdoor pond slider enclosures do not need heating. Provided that they are sufficiently large and deep, and you live in an area where the climate is appropriate for outdoor housing, the sun will heat the water within an appropriate range. According to Ernst and Lovich, pond water temperatures can range from 1-40°C with little harm to the turtles. Furthermore, because the water gets naturally heated by the sun, this often creates the desired microclimates for hatchlings and juveniles — further arguing that outdoor ponds are truly the best way to keep this species.

Because you are using electrical appliances near water, you will need a Ground Fault Circuit Interrupter (GFCI) if you live in the USA/Canada, or a Residual Current Device (RCD) if you live in the UK/Europe.

What about winter cooling/brumation?

As cold-blooded animals, when environmental temperatures drop, red-eared sliders lose their appetite and become sluggish or inactive. Every winter, red-eared sliders and other pond sliders go through a winter cooldown or brumation to help them survive this period of low temperatures and scarce food, and in turn this long period of rest helps regulate their hormones and has been correlated with greater longevity.

In other words, it is normal and beneficial for your red-eared slider to brumate every year, and it’s best to encourage this natural behavior. For more information, please read our page on brumation for red-eared sliders.


  • Red-eared sliders need an area of dry land to bask.
  • Basking surface temperature: 104°F (40°C)
  • Use a halogen flood heat lamp (preferably two) to create the basking area.
  • Minimum water temperature varies based on the turtle’s life stage.
  • Water heaters must have a plastic cover for safety.
  • Outdoor ponds do not need supplementary heating.
  • Use digital devices to track temperatures.
  • Heat lamps should be turned off at night.
  • Winter cooling/brumation is required for best health.

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