My tank levels have been great for a while now (meaning Ammonia, Nitrite, and Nitrate) except for my PH. My tap PH is fluctuating, but always between 6.8 and 7.8 (I test it before I add any water to my tank). However, unless I treat my tank with PH Down, it wants to sit up at 8.2. Our tap water is also very hard. So I'm hoping to replace the water at small changes with bottled water and have the tank PH and hardness lower a bit. I don't know what to use though. I've seen gallons of reverse osmosis filtered, spring water, mineral water, and drinking water. Maybe some of these are really the same? But I'm at a loss as to what should be used in an aquarium.