thank You guys for what you have told me uptil now. I have two more questions.

Q1. I don't understand how the filters work. What really does happen when you install a filter in your aquarium?

Q2. What should be at the bottom of the aquarium? Do you get it along with the aquarium? What is it called?

Thank You for everything that you have given me uptil now, I got lots of information from that but there are only a few questions that I still have.

Thank You!!