For my turtle I use two bulbs:

  • IR to make nice warm place for my turtle.
  • UV to get vitamin D and kill some bacteria.

What time should the bulbs be ON (from - to)?


1 Answer 1


First things first, let's briefly discuss the UV spectrum. The UV spectrum is split into three parts:

  • UV-A, which is basically heat.

  • UV-B, necessary for vitamin D3 synthesis.

  • UV-C, the harmful part of the spectrum mostly filtered out by the ozone layer. This spectrum is sometimes used to kill harmful bacteria and microorganisms in the water.

Before specifying the times, I'd like to suggest a plan of the lighting you could have for your turtle:

  • A UV-B mercury vapor bulb at the basking spot, the UV-B will enable your turtle to synthesize vitamin D3, essential for its health, but won't kill any bacteria, UV-C is used to kill the bacteria in water. And in case you didn't know, not all bacteria in the water are harmful, some are necessary for the biological filtration in the tank. You can also have a fluorescent over the whole enclosure so the turtle gets some UV-B while swimming near the top. You should have these off during the night.

  • A UV-A at the basking spot, this will provide heat for the thermoregulation of the turtle. I actually don't know why you can't use a heat producing infrared fixture instead, but turtles naturally generate heat from the UV-A part of the spectrum. This also has to be off during nighttime.

Some lamps produce both UV-A and UV-B

  • And finally an infrared ceramic heat lamp. This is the only lamp you can turn on at night. Even though it's not necessary, it's good to have in case the turtle wanted to warm up during the night.

    In terms of how long you should keep them on or off, you should seek to pursue the natural cycles, so naturally, when the sun rises, the UV lamps should be on. You can turn the UV lamps longer in the summer since then days are longer, and vice versa in the winter months. You can keep the UV lamps on for 14 hours during the summer and 10 hours in the winter, though twelve by twelve shouldn't be detrimental. And since we're on the topic of temperature, make sure you have an aquarium thermostat that keeps the water at an appropriate temperature. There are also some commercially available electrical plugs which you can set up to automatically turn on and off in a constant cycle.

  • I was also thinking to use e-zooo.com/Sera-UV-C-System-5-W/en where is UV-C but now I am not sure if I should use it? I know some filters have it inside of its system.
    – Luxqs
    Jan 6, 2015 at 16:02
  • @Luxqs you can use a UV-C filter if you want, but it depends on the size of the enclosure, usually these are used for large enclosures and to eliminate algal growth. What is the size of the enclosure. And the lights you're using are good.
    – Mozein
    Jan 6, 2015 at 16:25
  • I have 60L in aquarium and no problem with algal.
    – Luxqs
    Jan 6, 2015 at 16:37
  • 1
    Hi, the part about UV spectrum isn't really true. UVC is the most energetic, thus has the highest and most reliable germicidal properties and is used in sterilizing lamps, yes; but it doesn't mean that the less energetic UV wavelengths don't kill bacteria at all. UVB is actually capable of causing direct DNA damage and definitely DOES kill microorganisms, it's just that UVC is more efficient in doing so. One of the oldest disinfectant known to man is sunlight - and please not that UVC doesn't reach Earth's surface, only UVA and UVB does.
    – lila
    Aug 15, 2020 at 0:30

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