yeah scotch tape works, but I've found that if you put water or some sort of oil between the background and the tank, it will miraculously show up 60% BRIGHTER and more clear. I did that with my 10 gallon tank. I wet the back of the tank with a sponge and spread it all around, then placed the background on, secrured it with tape and took a credit car to squeegie the excess water from between the tank/background and I was totally AMAZED at how bright and clear it showed up. But with water, it's hard to do without getting little air bubbles and dry spots in the background, so there are spots and areas where it's dark, and areas where it's really bright and clear. I had read somewhere to use some sort of oil instead of water, because it won' tdry up and leave the bubble/fade spots.