There are three commonly used custom aquarium filters to select from when choosing your setup. Hang-on-Back (HOB) filters are the low-end, Canister filters are the mid-range filter and Wet/Dry filters are the high-end filters. Each has pros and cons, however, when used properly, can keep the fish in your aquarium setup happy and healthy for a lifetime.
In this post, we are going to explain Hang-on-Back (HOB) filters.
HOB filters are compact, inexpensive and, yes, you guessed it, hang on the back of your aquarium. These are intended primarily for freshwater use and should only be used in marine applications by the experienced hobbyist. They usually consist of simple, removable cartridges, which should contain three filter elements. Some still use a single all-in-one cartridge you replace each month. The advantage to the hang-on-back filter is ease of use. All you have to do is change one element every month in order to refresh your carbon filter. The downside, is you will be throwing away a large portion of the aquarium’s good bacteria with each cartridge and your aquarium will go through a short unstable period while the bacteria re-grow.
Most HOB manufacturers have thought of this, and now include a second cartridge just for the bacteria to grow on. This cartridge gets left alone or only rinsed every month while the other cartridge still gets replaced. Some have gone one step further and include three separate cartridges for mechanical filtration, chemical filtration and biological filtration. The benefit is the ability to properly maintain a bacteria culture in the filter. The down side is there are now three filter-elements to be maintained. They are still very simple to use as they are intended for beginner aquarists. HOB filters, due to their compact construction, only circulate the small portion of the aquarium water directly in front of the filter. For smaller aquariums this is a negligible problem but for larger, longer aquariums an alternative, or multiple HOBs, should be used.