Thanks for your suggestion. I have heard that people clean the barrels from time to time but I questioned as to how necessary it would be for me to do so. I have ran barrels like this before for 4 years and never cleaned them once with no issues but that doesn't mean I shouldn't have. My logic is that the water is only in there for a day or less, and if I go away then perhaps max a week, should I decide to leave it full before I go away. With all of the constant input of new water, sometimes 60 degrees, sometimes 80, does the bacteria really have a chancr to grow since the drums are being blasted with straight tap every time? Even if I add Prime right away I wonder how the introduction and constant flow of new water affects the need to clean barrels. I will have to do my research so thank you for bringing this suggestion to the table, I am always looking for ways to improve / rethink what I am doing. It seems like your suggestion to add Prime before I do the water change may be something worth implementing at the very least, I will look into bacterial growth in aging barrels to see what the deal with that is.