I could be off base here...but how does LIGHT remove a mineral?

The claims that they are expensive to run are off base....how expensive they are at purchase and to run depends on how big you go. You don't need a big one. My first I beleive was 8 watts? or something like that...it's been years and I no longer have the unit. But it wasn't much at all.

Apparantly the UV sterilizer is more of a personal taste type thing. No you don't have to have it...especially if you are growing 12 goldfish in a barrel. But it should be at least considered when someone is dealing with larger concentrations and higher volumes. Compare the cost of it, to the cost of total replacement of livestock.

I have run mine for several years, to date, nothing to my knowledge has suffered from nutrient loss. I have killed many plants, but I don't believe any of them were due to nutrient deffeciency. Usually it's something like the strawberries getting some salt or something like that. I can't blame the UV though for my errors.