Ed wrote:

Tullock's book
has a section somewhere in the beginning that talks about using natural
sea water.
Emmens "The Marine Aquarium in Theory and Practice" also has a section, which
has similar recommendations.

Emmens states that using the water immediately is "fairly safe, but risk of
disease is always present." If it cannot be used immediately, he recommends
storing it for at least 3 weeks in large containers in the dark. When you're
ready to use it, avoid disturbing any sediment which may have precipitated out.

He also states that mildly polluted water frequently causes an increase in
ammonia and/or nitrite levels, and these levels can remain extremely high for
months, so test these levels before use.

George Patterson
Coffee is only a way of stealing time that should by rights belong to
your slightly older self.