i was given a 55 gallon tank a few weeks ago. it holds water and has had water in it until about a month ago. when i started cleaning the tank i realized there is sort of a green color underneath the silicone on the sides. im not really sure how old the tank is or if your suppose to redo the silicone over the years but i was wondering if i should resilicone it or would it be to much of a hassle?