Definitely think its the silicone, I remember reading awhile back another member also used the GE 2 and had the same problem even though it wasn't list on the label. I'm paranoid when it comes to silicones and pay the extra money for the aquarium stuff. The piece of mind is worth it when you figure the cost of the fish in the tank, at least to me it is. It seems like these company's are always changing their formulas, and you don't find out until its to late. Feel bad for you.