sewage treatment reflection

In APES after school we did a project that showed us how water could be filtered. We also got to compete with each other to see who could get the cleanest water. What we had to do was get a clear bottle of soda and rip off the plastic around it. Next we had to cut the bottom of the bottle and write our names on the outside of it. After that we had to use any of the materials laid out for us like: cotton balls, polyester fill, gravel, sand, and coffee filter. Depending on our choice, we got to fill our bottle up with as much of what we wanted. The number of layers didn't matter at all. As we were doing this, we had to write out what we were using to keep track of the amount we were using. Next, we all went to Ms. Reid and she filled up our "sewage system" up with dirty water and while using the part we cut out, we held it under for the water to come up. As the water would dripped out, we got to observe how clean our water was or how unfiltered it was.
Once we were done with everybody's' sewage system, we had to line them up to rank them. Mine came in third as the cleanest. In order from cleanest to dirtiest: Justin, Briana, Me, Krystal, Alida, Jenna, Eddie, Henry, Nick, and Emanuel. I feel like if I added more polyester, my water result would have been much cleaner. But I thought as I was doing it that the amount I had was enough to cleanse the water. It was not much of a disappointment because my water came up as the third cleanest. I think comparing mine to those who were not as clean, I must have layered it more than others. Perhaps the amount of cotton balls or polyester I had was able to hold more of the dirt back. While others probably did not think much about layering it. I feel polyester was most effective because its type of fabric held up most of the dirt while the cotton balls just soaked up the water in general. The gravel just blockaded some of the areas the water could pass through. Also, the sand just soaked up the water.