This past week I've been observing my tank with a clown, bicolor blenny, and purple tang. I first noticed a white spot on the CB so have been monitoring the tank closely. A couple days ago i came to the conclusion the white spots were just tiny grains of substrate because they never lasted more then a day. well today my clowns swimming erratically and has a white film on his side (not the tiny white specs I've been monitoring ) but a large white film almost. I assume it is brook but am very inexperienced as this is my first saltwater tank. I did a few minute fresh water dip but don't know what else to do and I don't have a QT tank.