For 99.99% of cases, you do not want to mess with the pH. These products are very unstable and will lead to pH swings in your tank. Also, it can lead to other problems with the fish down the road. Most fish will adapt to your local pH. Just make sure you aclimate them slowly if your pH is different from that of your LPS/LFS
What is the current pH of your tap water and what fish do you hope to keep in there? Also, it is important to know your KH (aka alkanity), which tells how stable the pH will be. The lower the KH, the more prone to change the pH is.
