I can't really advise you regarding Nature2 or it's claims without exposing my personal bias about such products. That said, here goes:
Do they tell you exactly what's in it? If not, why? I've flippantly advised people to turn it off, cut it out, or pull out the cartridges. It may have a place but my guess is that it puts copper in the pool and I would not advise adding copper to a pool for a number of reasons. The first is aesthetic, copper stains pools, fingernails and light and colored hair green. Second (and more important) is sanitization copper is a pretty effective algaecide (really algae preventative) but a pretty poor sanitizer. Copper is dangerous because it can (with low FC advice) lead to a pool that looks clear(no algae) but can't kill the bacteria that gets washed away from the far end of a swimmers GI tract before it gets to the near end.