I have had flatworms for 2 years. There is so many they cove whole rocks and occupy my entire sandbed. I tried flatworm exit once and did what everybody said with water change and charcoal but still lost 3 fish and lots of corals due to toxins released. There must of been a few left and repopulated tank to the hilt over last year. SO tried natural route and bought a six line wrasse which has been in the tank for 5 months and population has not been touched. SO any ideas on how to kill these babys for good or at least have them head the other way. Would a velvet nudibranch be any good. I am desperate. Tank looks like crap because of these little bastards.