I was just reading about bleach and remembered this thread. Ironic that a sodium based product is so poisonous to saltwater fish and inverts...
"Environmental impact
No emissions of sodium hypochlorite from normal household or institutional use find their way directly to the environment. Sodium hypochlorite degrades quickly, primarily to sodium chloride, during use or in sewage systems. It also decomposes in soil, primarily to salt. Typical use was found to be not harmful to sewage treatment or septic tanks
Sodium hypochlorite is toxic when undiluted (5% concentration as sold), but is rapidly diluted or decomposed to harmless levels in soil or sewage systems.
Bleach is highly toxic to fish and invertebrates. In confined spaces, fish will attempt to swim away from the source. In addition, sodium hypochlorite readily disperses and degrades mostly to salt in surface waters, limiting impact."
http://en.wikipedia.org/wiki/Bleach