Thanks, Devon.
[1] This does not pertain directly but I found this interesting and somewhat relevant: from
http://en.wikipedia.org/wiki/Water_chlorination: When dissolved in water, chlorine converts to an equilibrium mixture of chlorine, hypochlorous acid (HOCl), and hydrochloric acid (HCl):
Cl2 + H2O <--> HOCl + HCl
In acidic solution, the major species are Cl2 and HOCl while in alkaline solution effectively only ClO- is present. Very small concentrations of ClO2-, ClO3-, ClO4- are also found.
Sodium salt of HOCl is, of course, the bleach - NaOCl = Sodium Hypochlorite .
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[2] From the link above (
http://www.pondplace.com/dangersofchlorine.aspx):
Here are example chlorine levels and what they can do to pond fish:
.006 mg/L will kill fish fry in about two days.
.003 mg/L will kill insect larvae, such as dragonflies.
.002 mg/L will fatally damage the sensitive skin on tadpoles, frogs, salamanders and other amphibians.
.01 mg/L is the maximum level that experts say adult fish can tolerate.
.25 mg/L is the level at which only the hardiest koi or other pond fish can survive.
.37 mg/L is the level at which all pond fish will die.
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[3] From WHO's Measuring chlorine levels in water supplies
http://www.who.int/water_sanitation_health/publications/2011/tn11_chlorine_levels_en.pdf
-- Water requires 2.0 mg/L of chlorine to destroy all organisms.
-- Chlorine needs at least 30 minutes contact time with water to disinfect it.
-- The optimum
chlorine residual in a small, communal water supply is in the range of 0.2 to 0.5mg/L.
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[4] From Free Chlorine Testing (also known as chlorine residual, free chlorine residual, residual chlorine) in drinking water:
http://www.cdc.gov/safewater/chlorine-residual-testing.html
.... the goal of infrastructure-based (piped) water treatment systems, whose aim is effective disinfection at the endpoints (i.e., water taps) of the system: defined by the WHO (1993) as: "a residual concentration of free chlorine of greater than or equal to 0.5 mg/L (0.5 ppm or parts per million) after at least 30 minutes contact time at pH less than 8.0." This definition is only appropriate when users drink water directly from the flowing tap. A free chlorine level of 0.5 mg/L of free chlorine will be enough residual to maintain the quality of water through the distribution network, but is most likely not adequate to maintain the quality of the water when this water is stored in the home in a bucket or jerry can for 24 hours.
... the Safe Water Supply (SWS) Program recommends for dosage testing that:
--- At 30 minutes after the addition of sodium hypochlorite (or chlorine) there should be no more than 2.0 mg/L of free chlorine present (this ensures the water does not have an unpleasant taste or odor).
-- At 24 hours after the addition of sodium hypochlorite to containers that are used by families to store water there should be a minimum of 0.2 mg/L of free chlorine present (this ensures microbiologically safe water)...
-- The SWS Program methodology leads to free chlorine levels that are significantly lower than the WHO guideline value for free chlorine in drinking water, which is 0.5 mg/L value.
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I trust your experience with tap water in Canada but I am trying to reconcile these statements:
".01 mg/L is the maximum level that experts say adult fish can tolerate.
.25 mg/L is the level at which only the hardiest koi or other pond fish can survive.
.37 mg/L is the level at which all pond fish will die."
and
"The optimum
chlorine residual in a small, communal water supply is in the range of 0.2 to 0.5mg/L."
I guess that the residual chlorine in your tap water MUST BE well below 0.01 mg/L?
