AQUANATURE CALISTRA EXTERNAL HANGON FILTER The Hang-On Filter provides clear water in the aquarium without making much noise. Adjustable the flow with a knob, which is super useful when you’re feeding the fish or if you need to change the flow for any reason. Filter uses disposable cartridges that are double-sided and filled with Activated Carbon ⚫ and Poly Fiber Floss. Versatile Filters for planted and marine aquarium.