You Need to Know About UV-B Lights for Turtles Main Picture

Turtles need UVB light to warm up, dry their shell, and to soak up UV rays. Here is what you need to know about UVB lights for turtles.

What Kind of Light Do Turtles Need?

If you have an indoor pet turtle or tortoise, it will absolutely, 100% need UV-B and UV-A light.

Indoor pet turtles need light for primarily three reasons.

  1. They need a light source that approximates sunshine, mostly for warmth.
  2. UV-A light is required for their metabolism, mood, and breeding.
  3. UV-B light is necessary for the production of vitamin D3.

All three of these things are absolutely critical to have. While your turtle might be able to get UV-A light from the sun or other sources, you will definitely need to get a light that emits UV-B rays. Below are my top 2 picks.

UVA UVB Reptile Light

uva uvb light for turtle

This is my favorite light because it emits both UVA and UVB rays. It also allows you to adjust the temperature and brightness.

Aquatic Turtle UVB & Heat Lighting Kit

turtle lighting kit

This is also a great light for turtles. The only downside is that it is pretty expensive.

Below is a video of me reviewing the UVA UVB reptile light, which costs less than $20.

Another great option is this UVA UVB combo light. I love this light because it is easy to adjust because it cat rotate 360 degrees. You can click on the picture below for more details.

If your pet indoor turtle does not have all of them, there is a very good chance it will stop baking, which can lead to various health defects sooner or later. You can learn more in my video below.

Why Turtles Need Sunlight

Both in the wild and in captivity, turtles need to bask.

Basking refers to when a turtle leaves the water and lays on a solid surface for an extended period of time. In the wild, turtles often bask on rocks and roads but they can bask just about anywhere the sun shines.

One of the reasons that turtles need sunlight is to dry out their shell and their skin.

Different species of turtle spend varying amounts of their lives in the water.

And when a turtle is in water for prolonged periods of time it increases its risk of contracting dangerous bacteria, turtle diseases, and fungi on its shell and skin.

Basking is a way to dry out and combat this. This is even more critical for semi-aquatic species of turtles, such as red-eared sliders and painted turtles. These types of animals live around 75% of their lives in the water.

Staying in the water too long can also increase the chance of turtles contracting shell rot.

But, that’s not the only reason they need sunshine.

Light is Needed for Warmth

They also need to bask for warmth.

The second way they combat those dangerous risks is by raising their internal body temperature. And the way they do this is by sitting out in the sun for a while.

Because turtles and tortoises are cold-blooded, they need sunshine to effectively raise their body temperature. This basically “cooks” any harmful bacteria out of their system. If the uvb light for your turtle doesn’t produce enough heat, it can lead to a respiratory infection like the turtle below.

Light Maintains Their Circadian Rhythms

They also need light for a very special reason.

Turtles need light to maintain their circadian rhythms.

When turtles are in the wild, depending on whether they are primarily nocturnal (active during the night) or diurnal (active during the day), they still have a certain “daily rhythm” with respect to how long they are active, at what times, etc.

If turtles only had a source for warmth, but not a source for light, it would throw off everything and cause tremendous stress and anxiety.

Now that we know that a turtle needs a light-source to provide warmth and allow it to dry out its shell (or a light source which mimics this ability), let’s discuss why turtles need UV light.

Why Turtles Need UV Light

Turtles need UV (ultra-violet) light.

And not just UV-B light but UV-A as well.

Both UV-A and UV-B light are critical towards maintaining their health.

Let’s talk about why turtles need UVA light first.

Why Turtles Need UV-A Light

Some articles may suggest that UV-A light is not as critical as UV-B light for a turtle, but that is not entirely true. Both are extremely important.

Turtles need varying amounts of UV-A light depending on what species they are.

They generally need it for three things:

  1. Help regulate their mood.
  2. To regulate their activity level and metabolism.
  3. Maintain healthy breeding and mating activity.

Also, visually, turtles are able to see much more of the light spectrum compared to humans.

This ‘colors’ their world in a much brighter fashion.

Without adequate amounts of UV-A light, turtles may not be able to properly see and experience the world around them.

Now that we know that a turtle needs a light-source replicating the sunshine, let’s discuss why turtles need UV light.

Why Turtles Need UV-B Light

Getting enough UV-B light is also critical for a turtle’s health.

Turtles need UVB light to maintain an optimal level of vitamin D3 production. Without it, they will be unable to process and use calcium in their bodies.

If a turtle does not get an adequate amount of the vitamin D3, it may lead to things such as:

  • Shell decay and limited growth.
  • Bone decay and limited growth.
  • Premature death.

Simply put, it’s vital.

Unfortunately, many beginner pet turtle owners aren’t aware of just how important UV-B and UV-A light is. Then they are astounded that their turtles die premature deaths despite the fact that they were seemingly “given everything they needed.”

This is why turtles don’t merely need any old fluorescent light bulb, but specifically-designed bulbs made just for reptiles.

So, when looking for UV-B lights for turtles, the bulb must be able to produce UV-B AND UV-A. If you have a tortoise, you should check out my article on UVB light for tortoises.

Now that you know why it’s important for turtles to receive UV light, let’s move on to which UV-B light is best for your turtle.

UVB Light For Turtles

Here are a few tips when looking for a good UV light for your turtle.

Steer clear of ‘full-spectrum’ UV lights. This is a marketing ploy. While these bulbs may produce UV-A and UV-B light, nearly all of them do not produce enough of it for your turtle.

This is a marketing ploy. While these bulbs may produce UV-A and UV-B light, nearly all of them do not produce enough of it for your turtle.

You should also avoid so-called “special or specialty” lights.

Many of these lights produce excess amounts of UV-A, which would not be healthy for your turtle.

The Best UV-B Lights for Turtles

If you want a long-lasting, high-quality, adequate-producing UV bulb, check out either the Zoo Med Combo Pack or the Mega-Ray Mercury Vapor Bulb. You can click on the pictures below for more information on the product.

Both of these bulbs are fantastic choices, and you really can’t go wrong with either.

For a more in-depth guide to UV light bulbs, check out my article on the best turtle light bulb.

The Zoo Med bulbs don’t produce as much UV-B light as the Mega-Ray but they still produce enough for your turtle, and will typically last around a year before needing a replacement. This is quite exceptional for UV lights in my experience.

The Mega-Ray, in particular, produces the most UV-B on the market and is also one of the longest-lasting.

How Much UV Light Does a Turtle Need?

One of the more frequent questions I get asked is “How many hours of UV-B light do turtles need?”

As a general rule of thumb, you should try to turn on your UV light when the sun rises and turn the light off when the sun sets. If this isn’t practical, it’s good practice to simply leave your UV light on for 8 to 12 hours.

If you only turn it on for a few hours a day your turtle likely won’t get enough UV-B and UV-A light.

And if you keep it on too long you may interfere with your turtle’s “daily rhythm”. You’ll also have a slightly higher electricity bill!


To summarize, turtles need light for 3 primary reasons:

  1. A light source to maintain their circadian rhythm and provide warmth.
  2. UV-A light to maintain healthy mood, metabolism, and breeding activity levels.
  3. UV-B light to help with strong bone growth, and prevent bone disease and premature death.
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