Water hardness dkh? What is it- what is right- how do you get there? I am very confused by the whole water hardness thing. I understand the general concept but I don’t understand how it all works and what the proper levels are. I also don’t get how hardness and calcium are linked together and how they interact…. I was hoping somebody could give me a nuts and bold breakdown about how it all works together. I would also like to know what the proper levels are and how I make sure my water stays there… Currently I have a RO water purifier. I use this to make all the water that goes in my tank. After I get it I mix it with salt and that is what I do a water change with. However should I be adding something to this mix to make sure my water hardness is at the proper level???? Need help.