Smallest Hang on the Back Filter?

Topic: I have a small 5 gallon aquarium and I want to put a HOB filter on it. What’s the smallest hang on the back filter on the market? Does it have good reviews and is cheap? What are some of the best brands to choose from? I need some help here.


*Awarded Answer
Posted by Jessica R: With a tank that small I would advise using a different style filter. Most people use an air pump with a “sponge filter” on the end of the air hose. As the air is pumped out of the sponge it sucks new water into it. This is actually very effective and that’s what people use on small tank setups. These sponges grow a lot of good bacteria and do well in small tanks for guppies, bettas, tetras, etc. What people will do is have multiple small tanks and get an air pump with multiple air outlets like this

Active Aqua Air Pump, 4 Outlets, 6W, 15 L/min
List Price: $28.95
Price: $27.32
You Save: $1.63
Price Disclaimer

Once you have the air pump you can then get the sponge filters. They are cheap and just hook up to the air line. You should squeeze these out maybe like once every 2 weeks.  I use these in a lot of my tanks and they are very effective. The reason people don’t use “hang on the back” filters in small tanks is because the filter pushes too much current for the fish. This sponge filter is a much better setup



Posted by Amanda E: The best small hob filter I found is the Aquaclear 20 filter. It has super good reviews and the Fluval Aquaclear line has been around for decades with best selling awards, etc.

  • I also have the aquaclear smaller version.
  • I have 6 ember tetras and 4 julii cory cats in a 20 gallon tank. (I am a beginner. I’ve only had the tank for 6 months). I was using an AquaClear 30filter but I’ve had a LOT of problems with the motor and impeller not working properly, stopping all together, or making loud popping noises. I left on a 5 week vacation and I thought it would be okay because I put petroleum jelly on the impeller shaft before leaving and the noise making stopped (I have 1 week still until I’m home) but my landlord just let me know that there’s NO water running through the filter and the motor is still, but hot. 🙁 I have no idea how long it hasn’t been working and I’m really worried. Unfortunately, I don’t know anyone who has the slightest idea how to fix it for me… How long do you think they can survive without any filtration? My hope is that they are all pretty small fish so it’s a small bio load for 20 gallons. What do you all think?
  • Are sponge filters a good suite for betta fish?
  • I swear this is the last question about this fish!This is Skimbleshanks. I got him 2 days ago and he’s had this little white thing by his anal fin. My first thought was parasites, so I fed him a little bit of daphnia and I’m treating him with prazipro. I’m just wondering whether anyone can confirm this or tell me what it is if it’s something different. A couple things to note, he is in a 2.5 heated, and filtered tank. He was also labeled as a girl in the store. And he’s still pretty small, so he might actually be a girl.
  • Have been out of the hobby for a long time, and looking forward to being able to get start a tank again. I do not have much space in my current apartment and can do a 30 gallon, but might be able to squeeze in and convince the wife on a 55. I know science has not changed, and ammonia to nitrite to nitrate is still key, but what about filters? I’m a fan of canisters not HOB. I tend to use mostly all biological in the canister and little to no chemical. When I used chemical it was Chemical Pure Charcoal. What brands/models do you recommend today? I was a fan of Eheim and their ceramics. What about heaters? I plan on stocking the tank with some variety of live plants, live bearers, small tetras, loaches, and cories possibly. Finally of course, lighting. Plants I do will be low to medium level light as tank will have to be closed well as I have 4 cats.

    I look forward to everyone’s feedback and hope I can add a little something here as well. In the past I did mostly salt.




Posted by Nate U: I got a betta in a 2.5 gal tank with small drift wood and two anubius plants and a decoration. I purchased a Tetra Whisper 1-3 gal filter. I absolutely hate it. The pump is loud and it bubbles out the sides of the filter. My question is Can i just ditch the filter and do weekly water changes and just give them a air stone?

  • Do daily water changes. Like 90% daily
  • Sponge filter would work too.. I have a ring feeder at the surface to help contain bubbles and have less surface agitation.
  • small filter hang on backwhere do you get them? which would you reccomend?
  • eBay, Amazon, local aquatic stores. And it’s really on you they all work about the same and you don’t need anything really big since it’s a small tank.
  • I agree that that filter is underwhelming. The idea is nice but the pump is weak and the filter plugs up too quickly. I also agree that the sponge filter will be a better option, but you’ll probably want a larger pump for it.
  • have my sponge filter in the right corner behind the decoration. They work great.
  • I have a finnex pure 5 hob on a 3g shrimp tank and they definitely do not get thrown around. Flow probably perfect for a betta. And it is silent. I modified mine with a stainless steel guard in the intake and threw in fluval biomedia. Took out the carbon insert.