Sponge Filters

[LisaM62]

Do they replace the filters that hang off the back of tanks?  Do I need both types of filters?

[Ryan S.]

Yes, they can replace fully or be run together if looking for extra filtration. Depends on your tanks needs. Important thing to remember is if you are replacing hang on back with sponge, make sure you run them together for several weeks before removing hang on back so beneficial bacteria can establish in sponge filter. 

[gardenman]

Can they replace a hang on back? Yes. Do you need both types? No. Do many of us still use both types? Yes. Why? Because each filter has different strengths and weaknesses. A sponge filter is a great biological filter. It will also trap and hold debris that's in the immediate area and keep your water clean. It's safer for fry and very small fish. A sponge filter doesn't let you use other filter media, like carbon, zeolite, etc. A hang-on-back filter (HOB) or canister filter gives you more options and tends to circulate water more aggressively. (Which can be good or bad depending on the tank occupants.) You can throw all kinds of filtering media into them. Especially the ones like the Aquaclears that don't rely on a specific type of cartridge. Because each has their strengths and weaknesses many of us use both to take advantage of all of the strengths and overcome some of the weaknesses.