baking soda worked like a charm
dear spar, I have added 1 teaspoon of baking soda into my PH 6.0 tank, and within a few hours(precisely the length of Starwars Episode III). The PH rose up to 6.6 and all fish seems fine. Thank you for the trick, now I'm going to start adding CO2 to the tank. any advise on how to plant "cabambas" so it won't be uprooted by my goldfish??