I used to have an Oscar, Jack Dempsy and a convict in a 150 gallon tank. My convict died of popeye after being moved to a hospital tank. I had to drain the 150 gallon tank so that a new floor could be put in and had to move the oscar and dempsy to a 20 gallon and they both died while in the 20 gallon - due to poor water conditions. How should I clean the 150 gallon tank, rocks, filters, etc. to make sure that there isnt any popeye or anything that could contaminate the water once I refill it. Is there a certain way, or it should be fine the way it is? I just dont want to refill the water and end up having the water infested with popeye where one of my new fish will catch it.