3 gallon nano reef or pico reef tank with HOB filter.
HANG ON THE BACK FILTERS OR (HOB FILTER) RECOMMENDATIONS FOR SMALL TANKS FROM 1 1/2 GALLONS TO 20 GALLONS, AND ALSO AQUARIUMS UP TO 55 GALLONS.
HANG ON THE BACK FILTERS
Keeping beautiful small to medium sized tropical freshwater fish?
For tropical fish like Guppies, Gourami, Barbs, freshwater angle fish, and glow fish, as well as smaller varieties of Cichlids then hang on the back filters should be fine. They are also nicely suited for maintaining small to medium saltwater fish only aquariums.
SMALL TANKS
For smaller fish tanks in the 10 gallon or 25 gallon range small cheap hang on the back aquarium filters often work perfectly fine. These more affordable filters start at very low prices.
But remember you get what you pay for, a cheap model may not work properly its worth just a few more dollars to get a better model. For a smaller tank a filter in the tens of dollars price range can be an important part in an affordable but beautiful smaller tank.
NANO REEF TANKS
Ironically these tiny inexpensive filters don’t just work fine on 10 gallon 20 gallon, and slightly larger fish tanks, but they work perfectly well on nano reef tanks in the 5 to 15 gallon range. These tiny more affordable saltwater reef tanks contain the most unusual and exotic, but tiny corals, invertebrates, and fish all kept happy with a small filter. Many nano reef tanks sold today come equipped with built in filters but you can put together your own kit with a clip on LED light, 10 pounds of live rock, some sand, and a small hang on the back filter.
KEDSUM 25GPH Subm
Another good and affordable choice for smaller freshwater and saltwater aquarium is the Kedsum hang on the back filter. These filters are good for smaller simple aquariums but are also useful for nano reef tanks.
They have two features that are common among hang on the back filters, and to be honest then do not excel as these first two features. They also have one very unique and helpful feather that helps it stand apart:
1) These small filters do an adequate job of oxygenation and gas exchange, purging carbon dioxide from the tank as they introduce fresh oxygen. The cascading flow design optimizes oxygenation as it flows water back into the tank. Of course, this is standard on all hang on the back filters.
2) They also act as a mechanical filter, the cotton filters out particles producing crystal clear water, this is also standard on hang on the back filters. The area that holds the mechanical filter was a bit narrow, even for a filter only designed for small tanks, this is a bit disappointing.
3) One thing that makes this filter stand out from the rest is the surface skimmer. When feeding fish good quality natural foods high in healthy fatty acids you introduce oils into the tank. These foods can result in a film of oily lipids on the water’s surface. Also, if water is rich in iron a thin film of iron reducing bacteria resembling oil can form on the water surface. Other organic compounds can also leave a similar film on the waters surface. This film blocks oxygen flow into the aquarium water’s surface. Though small, this filter can help with oil film removal using a unique skimmer not seen on most other filters. For this reason this filter should be considered for smaller tanks or even as an additional filter on larger tanks with a surface film / surface scum problem.
Pros: The above mentioned unique skimmer is very helpful for tanks with a surface scum problem.
Cons: Small mechanical filter compartment even for a small filter.
Suitable for smaller tanks up to 25 gallons and receives good reviews from many of it’s users.