Hi Sean, I have always used Furan 2 as a bath as it is intended for external use. The container of Furan 2 has a scoop which treats 20 gallons. I generally add salt to the tank when treating with Furan 2 as it seems to help. Generally treat for a minimum of four days. Personally I do not think it is a good idea to mix with food based on my first statement.
Pat