You Need to Know About UVB Lights for Turtles main picture
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Turtles need UVB light. They need it to warm up, dry their shell, and to soak up UV rays. Here is what you need to know about UVB lights for turtles.

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

But not just UVB light.

Indoor pet turtles need light for primarily three reasons.

Summed up:

  • They need a light source that approximates sunshine, for warmth.
  • UVA light is required for their metabolism, mood, and breeding.
  • UVB light is necessary for the production of vitamin D3.

All three of these things are absolutely critical to have. If your pet indoor turtle does not have all of them, there is a very good chance it will prematurely die or suffer from various defects sooner or later.

Let’s talk about why your pet turtle first needs a source that approximates sunshine, first.

Why Turtles Need Sunshine

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

Basking refers to when a turtle crawls out of the water onto some (usually elevated) spot and completely dries out. If you have ever seen a slider out enjoying the sunshine with its legs kicked out, you can be sure that it is basking.

One of the reasons that turtles do this is to dry out their shell and their skin.

Different species of turtle spend varying amounts of their lives in the water. Most species will spend at least half of their lives partially or totally submerged.

And when a turtle is in water for prolonged periods of time it increases its risk of contracting dangerous bacteria, 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, which 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.

As turtles and tortoises are cold-blooded, they need this in order to effectively raise their body temperature.

This basically “cooks” any harmful bacteria out of their system.

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 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 UVA light is not as critical as UVB light for a turtle, but that is not entirely true. Both are extremely important.

Turtles need varying amounts of UVA light depending on what species they are.

They generally need it for three things:

  • Help regulate their mood.
  • To regulate their activity level and metabolism.
  • 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 UVA 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 UVB light is 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, and then 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.

Thus, when looking for UVB lights for turtles, the bulb must be able to produce UVB and UVA.

Now that you know why it’s important for turtles to receive UV light, let’s move on to the next section, which is the best UVB lights for turtles on the market.

The Best UVB Lights for Turtles

When looking for good UVB lights for turtles, you have a few good options, but just to play it safe, here are a few tips.

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

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

Special or specialty lights.

These need to avoided as well. Many of these lights produce excess amounts of UVA, which would not be healthy for your turtle.

Not just any bulb from either of these two companies will do though, as you need a bulb that will produce the right amount of UVB light for turtles.

So, 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.

For a more in-depth guide to UV light bulbs, check out this article.

The Zoo Med bulbs don’t produce as much UVB 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 exceptional on the market).

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

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


To summarize, turtles need light for 3 primary reasons:

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

About the Author

Hi, I'm J and I'm the chelonian-obsessed creator of this website. Feel free to leave a comment below, as unlike a snapping turtle, I promise I won't bite!

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