I use a 20:1 combo of water wetter:distilled water with about a tablespoon of iodine thrown in to the mix to take care of the biological nasties. This mix has worked for me going on 6 months + now. To cut down on the tube discoloration/clouding from water wetter, I've found that if I let the mixture sit for a few days, a pinkish red distillate forms on the bottom of the container. Simply put the water solution in a new container, and you've got a kick*ss solution that will not cloud your tubes at all, and will only slightly discolor them. Further, removal of this distillate from the main solution does not appear to adversely affect the solutions potency (as far as corrosition inhibition, etc)...