How long do you bake baking soad for? And can you do a whole box and then store it in a container? Never mind said:I buy it in some big bags at Costco and bake all of it. Then I store it in a sealed container till I want to mix it with water. But at times I just put tablespoons of it dry inside the micron filter bag that I have on one of my return lines to the sump and that mixes it just fine with the tank water.