The best way to provide this is through the habitat's basking area. The lighting source that you use there can be used for UVB light needs. In fact, it is nearly a must for you to take into consideration.
But, you'll have to do some homework. The problem with most of the UVB lighting bulbs that you will find in your area pet store is they are not suitable for your iguana. Don't be fooled into believing they are even when they claim to be basking lights.
The problem is that they don't often provide enough UVB or they only provide it for a limited time. How long and how much UVB they provide is what is in question. With your pet's life at stake, you don't want to make a guess here. You'll find these offered throughout the web and they are by far the best source of UVB light for your pets. These are both great choices to consider, but you'll have to make your decision. Let's quickly break it down for you so that you can make a better decision.
Fluorescent tubing lights are easy to find. But, don't think they are all the same. In fact, those that are called full spectrum which you would possibly use to grow plants are not going to provide enough UV for your pet. Instead, a great choice is that of ZooMed Iguana Light 5.0. This is a great choice and has been used in several studies with excellent success rates.
If you decide to use fluorescent tubes, you still have to do a bit of work. First, make sure to purchase those that are made specific for reptiles. Second, place the bulbs no more than eight inches from where the pet will be basking. Anything more than that and he can't get the UV wavelengths that he needs.
Replace your UV fluorescent tubing at least every six to nine months. Even if they are still working at this point, they've lost all of their ability to give off UV lighting and are a waste to you. You may need more than one light to provide the right amount of light to your pet. In order to know this, use a Solarmeter 6.2 Spectral radiometer to help you to test the amount of output that you are getting.
Finally, don't place anything between light bulb and the iguana.
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