There is a common misconception is that people believe they purchase any type of incandescent bulb that it emits heat, it should emit UVB as well. It may be right but not all the case. There are many products of bulbs out there that has a similar spectrum, but not provide enough amount of UVB iguanas need.
So what is the most suitable UVB buld for your Iguanas? It is always better to purchase on the best UVB light for Iguanas that are specially designed for reptiles. Each type of UVB bulb has their own pros and cons but they should be emitting around 5% of UVB to meet the Iguanas need.
#1 Linear Fluorescent Lighting
This is the most common type of UVB bulb on the market that has been around the longest. Linear fluorescents do a good job of producing low to moderate levels of UVB. While not the strongest UVB producing bulbs on the market.
5.0 linear fluorescent bulb are good for Iguanas and they also can be able to cover a large range insider the tank. 5.0 UVB bulbs are designed to emulate moderate UVB levels, which ideal for iguanas.
The drawback of Linear Fluorescent Lighting is that they tent to lost their UVB after 6 months. That means you should replace Linear Fluorescent UVB Bulbs every 6 months, although many manufacturers suggest these bulbs remain usable for 12 months.
#2 Mercury vapor bulbs
Mercury vapor bulbs emit both heat and UVB. Mercury Vapor bulbs are relatively long lived, they can emit enough amount of UVB for your pets for about 12-18 months without need to be replaced.
Mercury Vapor bulbs produce intense UVB and heat. This also can be a drawback as the heat production make them more prefer for full sun animals such as bearded dragons than the animals that require cooler temperatures like Iguanas. However, if you use it in the large Iguanas terrarium, it can work great.
There is a note if you want to use Mercury vapor bulbs for Iguanas that you should place it further from the cage for about 18-12 inches, but base it on the heat emission intensity and how your iguana reacts to it.
#3 Compact Fluorescent Lighting
This is a good, affordable UVB bulb that can fit into just about any fixture on the market. However, the drawback of this UVB bulb is low UVB output and narrow focus. Due to this, you should use a fixture with a reflector will greatly increase the amount of UVB.
Generally specking, Compact Fluorescent UVB bulbs are not very efficient and producing UVB radiation in compare with the other types of UVB bulb. They should be use only above or near your iguana’s basking spot. Compact Fluorescent UVB bulbs should be replaced every 6 months.