Ok, so I went to my friends house and we were playing ping pong and I noticed a 29g tank. He said there used to be a goldfish in it 2 years ago. And he said I can have for free. But the water has been sitting there for 2 years and it looks nasty. He said everything works fine. There is a white film on the top and spiders in it. I'm not sure if the white stuff is bacteria or minerals. So the question: do I take it or will it cause problems?