I did a dumb thing about a month and a half ago.... I got the "not so bright idea" of using the water from our dehumidifier. I have used it in my irons for years because I was told that it is like distilled. Well recently some of my corals just haven't been up to par-in fact I lost a torch and am losing a Duncan. I couldn't put my finger on what was the problem since most of the corals looked alright. I decided to google dehumidified water. It is not distilled, it is considered gray water and not even recommended for your houseplants! Uhhg! I guess copper and aluminum can leach from the coils along with with picking up airborne contaminants. Wow, that's scary, its a wonder I didn't kill everything. Needless to say that I did 2 big WCs in 3 days and everything looks pretty good. Lesson learned. I shared just in case I am not the only one out there who would do such a thing.