Grand total here about 2 tablespoons gets added to one gallon of water for them. That also adds a bit of a familiar taste/smell to the water. So if and when you have to change waters there is something familiar smell and taste wise.
sorry to hear about your couch but did you hook science class? i make a paste of vinager and baking soda then apply it to the item i want to clean( jewelry etc) for water bottles try lemon juice, salt and an ice cube or two. swish this mixture around and let sit 10 minutes or so then rinse.(don't be stingy with the lemon or the salt)