Is tank safe after meds

[preswash]

I have treated a discus for worms with Metronidazole for 10 days. He won't eat and has white poop. There was a female with him that showed no signs of worms. We removed her. We left the sick fish in the 40 breeder alone for another week. Then tried PraziPro for 10 days same tank. The fish still wouldn't eat and is getting thinner. Moved him to a hospital tank. Soooo... now I've got a 40 breeder with no fish in it. Its a planted tank with undergravel filter and a penquin 330 hang on back. Crystal clear water. I will run a charcoal filter on it and give it significant water changes. But... I'm afraid to put any fish in it without a complete breakdown and cleaning. The Hex or parasites or whatever it was or is could still be in there... right?

What do you guys think or suggest? 

[Colu]

Parasites will die off with out a host I wouldn't put fish back in your tank for two weeks you could put a dose of prazipro in the tank and leave one week and then do a water change to be on the safe side also you could try soaking your fishs food in seachems garlic guard to help simulate it's appetite

Edited May 6, 2021 by Colu

[Brandy]

What @Colu said.

Most parasites die rapidly without hosts, and need a fish host if they are a fish parasite. Two weeks is an arbitrary length of time based on the average and common parasite life cycles, but still a good rule of thumb. I would clean and vaccume the substrate during the few weeks you wait, and then you should be safe to reintroduce fish.