A freshwater aquarium sump is a chamber that is used to hold extra water for your aquarium. This chamber is placed below the main tank and is connected to it via tubing. The sump also has a pump that will circulate the water from the sump back into the main tank.
The purpose of a freshwater aquarium sump is to provide a place for filtration media, such as activated carbon or biomedia, as well as to increase the overall volume of water in your system which can help stabilize pH levels. Sumps can also be used to house aquatic plants or even fish if you have the proper setup.
To set up a freshwater aquarium sump, you will need to determine where you will place it and then drill holes in your main tank and/or stand so that you can run tubing from the main tank into the sump. It is important to make sure that these holes are sealed properly so that there are no leaks. Once you have done this, you can then fill up the sump with water and add any desired filtration media or plants. Finally, you will need to connect the pump and make sure that it is working properly before adding it all back into your main tank.