Science Buddies: "Ask an Expert"

Do I have to leave the aquarium pump on during the whole entire project? Or only when I test? Is it normal for the salt bridges to be a jelly like substance? This is for the Waste not want not project. Thank you.

[Administrator note: project directions: https://www.sciencebuddies.org/science- ... from-waste ]

Hi -

1. The cathode needs to have oxygen (see paragraph 2 of introduction and the diagram there) and the purpose of the aquarium pump is to oxygenate. So yes, it needs to be on the whole time you are running the microbial fuel cell.
2. The salt bridge is a 3% agar solution; when set it should be firmer than jell-o but not solid.

Hope that helps!