I have a tank which since I set it up a few months back has caused most of my fish to die then one pleco hanging on but I don't think he's in a particularly healthy state. It's a planted tank with dirt at the bottom capped off with sand. The water parameters are fine nitrate nitrite ammonia etc on every test I've run for the last 3 months. However the tank has been played with algae growth. A red algae of sorts. I used chemiclean and an algae medicine but nothing has worked. Have now decided to give up put more remaining fish into a quarantine tank and eventually move them into another Aquarium with my other fish. The only thing I'm concerned about is it somehow contaminating my other fish tank, is there a way to limit the risk of contamination?