Help! I have a 65 gallon tank that had beautiful, exotic goldfish in it. I have the water brackish and have live sand in it. I also have live plants. My fish were happy, healthy and loved the sand. A couple of weeks ago I introduced a new fish into the tank without quarantining it first. It was beautiful but had external parasites. It died and has killed all but 2 of the fish. Those 2 I have removed from the tank and are doing well. My question is, while replacing everything else in the tank do I have to remove the live sand and the plants and start over with them, too?