1. The problem statement, all variables and given/known data Doing a science project for school. I have a fish tank and a divider separating one colored liquid on one side and another colored liquid on the other. I need it air tight initially, but will later remove the divider to allow the liquids to mix, demonstrating diffusion. 2. Relevant equations None 3. The attempt at a solution I have a tank and an acrylic divider. The issue is how to make it air tight initially while allowing the opportunity to remove the divider and allowing the liquids to mix. Any ideas? Thanks, and sorry if this is too juvenile of a question.