hey skunk the blue stuff in the port a johns is corrosive , I used to deliver it from the manufactuers .its made with some bleach or alkali in it , i would recommend a complete tear down on nina , then wash her in a bleach/water solution ( 1/2 cup bleach with 5 gallons of water or follow the NSF guidelines on food equipment sterilization ) and a heavy hot water rinse after words , just to make sure you get out all the alkali not including anything else that might be in there . most important wear gloves and DO NOT use any acids or ammonia with this solution you will liberate the chlorine from the solution .