The 5.0 is equivalent to a T8 I have used them in smaller tanks like 20 gallon and they have provided plenty of UVB --- this comes from a person who is a vet tech and experienced people who have had bearded dragons for over 20 years -- I am going to take their word over yours -- 5.0's are mainly used for aquarium use but can be used for reptiles as long as the distance correct and no cover over the bulb