I have also had an ongoing problem. I used flat worm exit twice, still had them. I resorted into taking my live stock out, took out all base rock, and only left in coral, then I added two yellow damsels and starved the tank. I did this for three weeks, tested two of my rocks with coral on it, no flatworms. So with my fingers crossed, I have now set my tank back up. It has been 5 days I will let you know if this worked.