Yes, you need a gravel vacuum to remove 25-35% of the water once a week while sifting through the gravel with the other end of the tube. Then you add dechlorinator to the tank, or to the new water, and you make sure that the new water is the same temperature as the rest of the tank water before adding it.
Seachums prime or Amquell are great products to use. They remove chlorine, chloramines, heavy metals, and detoxify nitrates and nitrtes and ammonia, "temporarally"
Seachums paraguard or other stresscoat product is another good thing to add, but avoid most other chemicals.