Do you need to add dechlorinator to distilled water?

All the nasties such as chlorine, heavy metals and chloramine are removed by the distillation process. However distillation also removes most trace elements which causes the pH to crash to dangerously low levels. If you added untreated distilled water to an aquarium containing fish it would easily send them into a state of osmotic shock, which eventually results in death. To add vital trace elements and minerals back to the water and also to raise the pH and hardness you can purchase special additives from aquatic stores.