718655fb_at_Conundrum__Mackinac_Center___3
[0] Filtration [1] Filters prevent organisms from entering/exiting ballast tanks. [2] Speedy. Can retain organisms in natural habitat. No chemical byproducts. Removes suspended solids. Readily available. [3] 
Expensive. Not effective against bacteria and viruses. Potential for clogging and slowing flow rate.
Great Lakes, Great Conundrum [Mackinac Center]
3