I am curious how many people that have a hydro running are actually using Reverse Osmosis water? I know for salt water tanks it is a must. Actually for reef tanks we take it a step further and use deionizer. Is anyone using water that has been left to air out for a few days? I am using RO water but its a pain to get it because I have to haul it from one room to another. I don't want to buy another RO unit just for the hydro.