Why make them a model? They function just as well as normal brushes which would actually solve the ugly lighting. People should see the green goo though. It's the goo that's bugging out. Actually, I just realized you made the goo in the reactor a water material. That's not gonna work. Water materials need to have a continuous surface rather than patches of goo. Otherwise you'll have "holes" in the texture and the water shader does not like that at all, thus borking out. I think it's better to remove the goo texture and make a custom water material that has a toxic green color.