I went to the store & bought 3 gallons of reverse osmosis water which has a perfect pH of 7.0. (Needed the jugs for water storage) My tap water is 7.6, rather alkaline. I found after testing water from my Brita filter it was about pH 6.0! Since I only am doing 1.5 gallon changes in my 6 gallon tank every couple weeks I will simply do 50% tap, 50% Brita once I use up the RO water. I tested a 50/50 mixture of this & got a pH of 6.8, about what I want since I will eventually be adding Tetras. Since the water changes are gradual & small the pH changes will occur over time. The Brita may also help reduce the GH a bit from regular straight tap water.