Unless you own extremely sensitive fish, there's no real need to keep the ph at exactly 7. Adding chemicals gets really old too. My tap water ph is about 6.2 to 6.4 . The gh and kh tend to read low too, so I use crushed coral in my filter to raise the hardness, thereby buffering the ph so it won't be prone to suddenly crash. Swings in ph are what's really hard on fish instead of any need for an exact number. I change out 10-20% of my water about twice a week, so I'm not throwing a bunch of low-ph water in at one time.
I don't know if any of this is helpful, but if your water is also soft, it may work for you easier than messing around with adding chemicals all the time.
to raise ph-- crushed coral or oyster shell (like for chickens at the farm store)
to lower ph-- peat in filter or driftwood in tank will help too
If you need to make a big water change and you want to match the ph to the tank water, a pinch of baking soda will do, there is info online as to how much to use, but I'd only do that if I had buffered my tank water with crushed coral or shell so it wouldn't swing low again later. I think this is right, but you need to wait for others more experienced to weigh in on the matter.