ph swing

Hi I'm new and have a question regarding PH lowering. My tap water normally comes out at 7.4 and I have been told that 6.5-6.8 max is optimal for the fish I keep. PH has never presented an issue for me as the fish I have have always appeared to be fine in the water range I currently have...

I'm setting up a new tank for a black ghost but my tap water ph is about 8.2 Now i can set it up from a store bought RO water, but it will be really hard to get in times of emergencies. so the Other option i have is to use a lot of drift wood and almond leaves to naturally bring the ph down...