Well, that got your attention. You’re probably thinking one of three things right now
1) Why? What’s wrong with my hang on the back filter?
2) Agreed, throw em away
3) Yeah he’s drinking fish water or something that’s for sure.
Any of those answers are a valid conclusion to the title.
However, here’s what I’ve come to learn from my experiences using every filter under the sun, specifically with HOBs. (seriously, there’s only one I can think of that I’ve never used).
The first thing that comes to mind when I think of a hang on the back filter, is that it’s an eyesore. I used them for years and sure, I didn’t care what it looked like as long as it did its job. But the filter in question uses significantly more space than most other types, simply because it requires space either behind the tank or on one of the sides, and cannot be tucked away under the tank like a standard canister filter or a sump. This doesn’t bode well with me, especially when I like my tanks as close to the wall as I can get them, to save space and to make them slightly more aesthetically pleasing.
One of my biggest pet peeves is cord and cable management. And the HOB is another plug in the wall. Now, there are a few exceptions here. The reason I say this is because I prefer sponge filters. Yes, they also require an air pump and thus an outlet, but this can also power multiple sponge filters and will cut down on overall power usage as well. Especially with owning multiple tanks at the same time (I currently run 5 tanks off of sponge filters and one industrial air pump).
Now onto why sponge filters are the better option of the two... in most cases. The best part about a sponge filter is that it's internal to the tank, meaning it sits inside the tank. This is beneficial for multiple reasons, but here are the main ones.
First, it keeps the water where it should be, inside the tank. HOBs need to pump it out of the tank into its body, and back into the tank. This can be a disaster waiting to happen, and more than enough times in my life I’ve spilled water behind the tank (WHERE YOU CAN”T REACH IT) while trying to clean a HOB. Continuing on the fact that it sits in the tank, if you were to have a power outage, this means that all the beneficial bacteria and the biosystem you have created will remain alive, instead of likely dying in a HOB or evaporating much faster (I’ve had power out for over a week straight but that’s another discussion about what to do with your tanks).
Lastly, with the filter body inside of the tank, the fish will naturally clean it which a HOB cannot do. By this I mean the fish will eat away at dead matter, old food, or whatever the sponge picks up. Obviously, a HOB cannot do this since the fish can’t reach it. One advantage of the HOB is selectable media, and possibly more filtration depending on the size of it. That means that you can put multiple different micron sizes of sponges, bricks, UV lights, whatever you may need inside of the HOB. But this also is easily done without a HOB by putting rocks, wood, or bricks in your tank to filter the water. To conclude I’ll leave you with these thoughts.
A sponge filter is easily installed, sits in the tank, is cleaned easily, and requires no internal maintenance. A HOB sits outside the tank, the impeller can wear down over time, the media clogs easier, takes up more space, and can be very loud.
Now if you’re dead set on getting one over the other go ahead, don’t look at me to tell you how to run your tank. I've used both and can't tell you that you have to get one over the other, or that one won't filter your tank properly, because both will. However, if you’re open to the idea of setting yourself up for success, and reducing stress on your tank and yourself I would highly recommend a sponge filter!
Here's an example of how I use mine, and what they look like. Both are pictures from my 40-gallon breeder. The fish featured are Panda Garra, X-Ray Tetras, and Ghost X-Ray Tetras.
