A few years ago my cousins did this really cool soda geyser. This thing shot many feet in the air. The boys and I thought we would give it a try. Even though we didn't have the neat little tube my cousin had that stopped the mints. Joey came up with using an empty pill bottle upside down with a hole cut into it. It only held 5 mints so we fit a toilet paper tube around the bottle so it would hold all the candies. Jordan made a stopper out of cardboard that we could pull out of the way with a long piece of yarn. We gather some original Mentos candies, some soda, and our own homemade tube, and headed to the park. (There was now way I was chancing having soda explode all over my yard). We set them up, Joey was first, he yanked the string and we watched the soda shoot up a whole foot from the bottle. Not what was supposed to happen. Jordan thought he'd try dropping the mints in with out using the tube. He managed to get 5 or 6 in before it started to erupt, again only about a foot high. Jake used our contraption but only put in 5 candies. His only bubbled out the top. Determined to make this work they even tried shaking the bottles with the mints that were already in there. They tried to shake up the soda and drop in a few more mints. It just wasn't happening for us.
Although our geysers weren't nearly as impressive as we had hoped they would be, they were glad we had attempted them. At least they did something, even if it was just a fizzle. We are going to shop around for one of those tubes, so we can send soda flying higher than our heads. I have heard that the trick is to use Diet soda, so we will give that a try too. It may take us a couple tries but eventually we'll figure it. I'll post pictures when we finally get the good geysers going.