It all depends on how low your pH is. If it is off by a few percents than usually a water change or two will bring it back up. If your pH is really low than you will have to use buffers. I had a pH problem and my lfs
gave me enough for three doses and haven't the need for it since. I would highly suggest using Aquavitro. They have great customer service and will give you the best advice when using their products.
If your tank is currently in a cycle than that will explain your low pH due to ammonia. Wait a few more weeks for your cycle to complete than test your pH again.