Learn early and well - modification of your source water carries much hassle, significant expense, and serious dangers to your fish. Other than for breeding purposes, most fish are highly adaptable to water hardness and pH. Commercial products that attempt to "correct" your pH rarely do so more than briefly - hours to a day or so - thus subjecting the fish pH roller coasters. That is many times as harmful as adaptation to a different and stable pH.
Stability counts.
