I went downstairs to hook up my tap lines to my keg (they lay in their box when not in use) and discovered that some mold had begun to grow in the lines. What should I do to clean them out / keep them clean in the future?
+1. If you really want to clean them, I'd try some hot beer line cleaner and then maybe some bleach+vinegar as recommended by the owner of 5-star chemicals. (The bleach+vinegar will act as a sanitizer and also bleach the color of the mold)
As far as storage I have a keg that always has blc in it, I run it through the line until the beer is out, then leave blc in it. When I want to use that line use other Kevin full of water and flush it out.