I use 2 sponge filters rated at 55-75 gallons in my 110gallon Angel tank and they work well enough. I added a small 30 gallon HOB just to help skim the surface of the tank and add mechanical filtration, but you are right you need to gravel vac almost every water change. I do have 18 Angels approximately the size of the bottom of a pop can and then 9 smaller bristlenose and 1 emerald green cory cat. Awesome room though, great work!