It's best not to alter your pH (really, we are talking about hardness.) There are some situations that will warrant changing your hardness to suit a particular type of fish, but if you got your fish locally chances are they are already acclimated to your hardness (and pH.) Altering your hardness (pH) will force them to adapt to a foreign hardness (pH) and will stress them out.
It's best to leave well enough alone
pH and hardness are different
Yes, often. But not always. Hardness refers to the amount of disolved minerals. Most of the time these minerals will raise ph. But not always.
Plus I wouldn't offer someone advice on what to do about their hardness without having them test it. You just don't know what it is. After all, I have fairly hard water, with a ph that sits just below 7. Why? Because I run co2. This lowers my ph, but not my hardness. They are separate. And should be treated as such.