I will point out that it will corrode the next bulb as it in he light socket now so it just keeps growing/ eatting away. I new fixure and light will be require but would need to figure out the problem or will happen again.
it prolly humidity , and the high temps causing it . I agree switch to the belly heat will solve a lot of it as well and covering the top to keep th heat in . or switch to the tub system they work great. I got a cinny here on my desk healing up great after needing surgery .