I needed to attach a pipe to a 55 gallon tank to use in a water tower. My first attempt was not so awesome. Then my brother in law showed me a product called Uniseal. These little rubber gaskets allow most pipe sizes to be used to attach to about any tank as long as the tanks walls are not to thick. In this video I show you how to install a 1-1/4″ pipe into a 55 gallon tank. You should be able to use a hole saw to make your project faster.
Be sure to buy your own in my Amazon store here on Land To House: