What do you mean by doubled his dose? The ratio of Sea Salt to water is important. I have to add slighly more salt that the recipe to get results. Two rounded tsp. rather than two level tsp. per 32 oz. of water. Have your husband try slightly increasing (or decreasing if that doesn't work) the Sea Salt amount.
BTW, I am on day 4 myself. I get encouragement by just reading the posts here.
John