Hello IA...
The majority of aquarium fish will tolerate a pH between 6.5 and 8. If your tap water tests out somewhere in this area, then your water should be fine. The majority of aquarium fish will adapt to the majority of public water supplies.
You can get some some floating plants like Anacharis and Pennywort. These two love acidic water and may help raise the pH a little. Some other good plants are Anubias, Java fern, any of the mosses and Cryptocoryne.
If the water stays acidic, then large weekly water changes will maintain stable water properties and at least the fish and plants won't be subjected to changes in the water chemistry.
B