I have a new baby Ambanja about 2 months old. He is in a 24"L x 12"W x 24"H screen enclosure. I purchased a reptisun 5.0 bulb for him and it is an 18" I used to have a 24" but the fixture went out and all I could get a hold of was a 24" fixture and an 18 " bulb. I was thinking of ordering a new 24" hood that holds the 24 " bulb but am not quite convinced I need to. At about 4.5 to 5 months old I am going to move him up to a 24X24X48 enclosure. My question is what is the difference between the two bulbs in regards to UV? I assume a bigger bulb = More light which is not too important as he is next to a window. I just want to be sure it has enough UV. Is it enough for my small cage?