Hey guys so I was at my friend's house last night and he's having a problem with flatworms in his tank. He bought flatworm exit but still hasnt used it because he's scared it could nuke the tank. It's a 40g breeder and a 13.5 Evo. Any advice or info would be very helpful. We're not sure what type of flatworms they are but corals look fine as of now. Please let me know what you guys think.