7.2 is not bad, the worst thing you can do IMO is chemically treat your fish tank when its not a necessity and cause unnatural PH changes. Id rather have a stable PH then one that is constantly fluctuating with chemicals. If you want to gradually lower your PH, add some driftwood. My PH is higher than yours; your fish will adapt to your PH as long as its consistent.
A constant pH is what you want. Playn with pH is asking for trouble. Driftwood or peat can lower it but then every water change your pH is gonna go up some & then slowly decrease again. I'd leave it at your tap pH.