No, do not mess with your water. Instead, acclimate the fish to your water conditions. This is done by placing the fish, and the water from the LFS, into a container. Every 15 minutes, add a cup of water from your tank. When you fill the container, remove half the wateer, and repeat. Do this a total of 3 times, over the course of several hours. Then net/remove the fish from the container and release them into your tank.
This gives them the chance to get used to your tank conditions, which is infinitely easier than changing the water conditions. The so-called instand fix additives seldom work for long, and most often result in yo-yoing conditions that are very bad for the fish.
