Why sea water is not permitted for veg oil tank cleaning

Always Use fresh water for making the cleaning solution, uses of sea water entire heating coils have chances of hard solid salt deposits and salt deposits could become difficult to remove. But if uses of sea water for making the chemical solution is only option then during cleaning operation First, stop the steam in the heating coils at least 30 minutes before stopping recirculation. Finally rinse the tank with fresh water for 5-10 minutes immediately after chemical recirculation.