718655fb_at_Conundrum__Mackinac_Center___3
[0] Biocides [1] Chemicals such as chlorine, bromine or iodine added to ballast water destroy organisms. [2] Can be effective on all organisms at varying concentrations. Easily stored. [3] 
Chemicals can corrode tanks, pipes and pumps. Potential for environmental contamination and toxic exposure to crew. Expensive. Lack of research on interaction between biocides and sea water.
Great Lakes, Great Conundrum [Mackinac Center]
3