Goldfish water hardness, alkaline and ph?

Honestly, the best thing you can do for your goldfish is to leave your pH and alkalinity alone and not try to lower it. Goldies are more tolerant of high hardness then low. As long as your water is stable, your goldfish will adapt to the level of hardness in your water. pH is not as important as people seem to think it is, especially with hardy fish like goldies.