Flatworm Exit made by Sailfert is the best. Quick and easy like the others say. Just don't use the BlueLife brand i have used that before and the flatworms came back after multiple treatments. I have never had a problem with Sailfert's Flatworm Exit but you want to follow the directions really good and don't skip a step. Especially the sucking them out part. Use airline tubing, that works best.