my heat lamp and uvb dont overlap which i know is recommended. the reason is because when they overlap the basking spot doesnt get hot enough. another reason is that my uvb is mounted inside but pulled as close to the top as it can so when they overlap my uvb fixture gets extremely hot. he spends time under both of them so i dont really think its a problem but i want to make sure its not necessary. another question is i know my uvb bulb needs to be replaced every 5-6 months but does the fixture ever need to be replaced? like will it start to affect the strength of the uvb or do i use the same one until it stops working? do my heat bulbs need to be replaced like the uvbs do or do i use them til they burn out.