We can drink water with enough heavy metals to cause damage to fish without being able to taste it. Same with a lot of contaminants. We are far less affected by impurities in water than fish are.
I would not be comfortable ingesting levels of contaminants (especially heavy metals) that would be harmful to fish.
You're right about not being able to taste heavy metals, that's why I recommended testing. If someone is drinking water that is unhealthy for fish due to heavy metal contamination they should be more worried about their own health than that of their fish.
That was pretty much the reason I just kept buying it... just in case.
I'll have to look at prime or that waterlife haloex you mentioned, blackghostuk. I've seen prime countless times at the store, but never thought it would be considerably cheaper... That's pretty cool. lol
