From their own website, and what was that stuff called, that they shoot into body's after dead to keep the body good for extended amounts of time? That is also in prime hence why I say any water conditioner are pure poison.
Formaldehyde? At any rate, before calling something pure poison, you have to know the solution strength of the said toxin, LD50 rate at its pure form, and much more. Apples and especially their seeds contain cyanide, avocados contain persin; many, many of the things we eat have safe amounts of technically "toxic" chemicals. And if dosing by instruction, you're only putting two drops of Prime per gallon of water. That's one part Prime to 37,854 parts water. And in virtually any case of a water change, it was added to the aquarium at least a week ago. Besides extreme dilution, the chemical reactions it goes through when added to chlorinated water, and breakdown of said chemical over time have to be factored in. I'm not saying that Prime is safe, but I am saying that if it was pure poison that it would not likely be safe to use on the most sensitive aquatic creatures that can kept in a glass box.
So these minerals are just natural? (no chemicals)
Important to point out here that all matter is made up of chemicals, whether natural or made in a lab. Water is H20, etc. Amanita mushrooms are as natural as organic life comes but can kill a human being who ingests even a tiny mushroom. Some organic pesticides are classified as more dangerous than their conventional counterparts; the chemical structure, not where it came from, determines toxicity.