Ive got my pigs water supply in a 50 gallon plastic drum. Its connected to a nipple that they drink from. So far its working great. It seems to last about a week or so. So every 3 or 4 days I top it off. I noticed today that the inside of the drum was a bit slimmy. I drained it & scrubbed down the sides & rinsed it out. I add apple cider viniger to try & keep the water fresh. Is there something else I could use. Or do I just need to rinse it out every couple weeks. Jay