Humans can tolerate chemicals at levels that would be otherwise fatal to every organism in the a pond. Heavy metals and hydrocarbons are two prime examples.
Some water softening salt is Potassium Chloride. The resulting Potassium lading flush would most likely result in difficult to control algae blooms.
Crissnow- If any of the water originating from the house is coming through Copper piping, this could also cause potential problems as heavy metals are both acutely and chronically toxic to all aquatic organisms at extremely low levels.
Originally Posted By: Cecil Baird1
Originally Posted By: Instar
The salt in itself is probably not cause for concern. The problem arises in the additives in many water softener salts. If you are using Morton's in the BLUE bag, you have no cause for concern, but if you are using Morton's in the YELLOW bag you are adding other chemicals to the pond's water column that may have a toxic effect at very low levels (micrograms/Liter). The addition of ANY non-naturally occurring compounds (chemicals) will alter the natural balance of water quality to a lesser or greater degree. This is exactly why the EPA has established fresh water quality guidelines, to aid us in protecting the ecological balance of our waterways. Choosing not to follow thee guidelines, or basic common sense for that matter, is inviting disastrous consequences.


What chemicals are we talking about that are harmful for the pond but not harmful for us to drink?