Salifert Flatworm eXit is a safe solution to get rid of flatworms in your tank. It is perfectly harmless for the reef inhabitants; SPS, LPS, soft corals, fish, snails, starfish, crabs, and pods. But definitely deadly for the flatworms. If your tank is heavily infested, Flatworm eXit will not be the cause if you lose livestock. The issue is that if many flatworms die at once, their toxins reach lethal levels quickly and this, not the product, can lead to deaths in your tank. Flatworm body juice can be toxic for the reef when present in high concentration.