I am planning on using water from my dehumidifier for my tank water changes. I have super hard water in my area and like to keep South american fish that tend towards the soft side. I know I can go and buy water RO water form the fish store or even the grocery store. I am wondering though if water from a dehumidifier or an air conditioning unit will work as well. This is water that is pulled out of the atmosphere so I figure it should be soft. Anyway has anyone else done this? I think this will work. I will go and test this water and find out its parameters to see if this is what I want.