How Do You Clean Hard Water Stains From Glass Aquarium?
If your water is that hard, and you are keeping fish that prefer a lower pH, then RO water is the best thing to use. However if you are keeping fish that thrive in higher hardness, you might not be able to do much. In my area the pH is 7.7, KH is 13. If I wanted to lower it to say 6.0, I would probably want to mix ratio of 60-75% RO to 40-25% tap.
