i have a 180gal with 8 reds and most of them have wite stuff on thier gills. they are constantly rubing there sides on the gravel. and off the driftwood and heater. i bought some aquarium salt and did a 50% water change adding alot of aquarium salt and after a week they are still doing it. what should i do? im useing carbon in the filters.. i have 1 aqua clear 500 and 1 aqua clear 300. think maybe i need more filteration? i told my mom to buy me another aquaclear 500.