Do i need to treat tank water for columnaris (body fungus) while treating my fish?

i have a serious body fungus issue in my tank. thought it was ick for a long time, so it was not treated appropriately. Some of my gravel has that white, stringy, cottony-looking stuff on it. I don't know if I should replace the gravel or if Maroxy will handle that? I have 4 striped raphael catfish and some platy in the tank and they are all affected!!! I've had these fish for almost 5 years and don't want to lose them. I am three days into treament with Maracyn and Maroxy and they are looking better, but my concern is the water itself and ornaments. Please help!