There are a lot of hang on back (or HOB) aquarium filters available. So, in this piece we’re going to have a quick look at each of them to consider the pros and cons.
Penn Plax Cascade
The Penn Plax HOB filter is a quiet runner—so if you have a show aquarium in your living room then the Penn Plax might be the choice for you.
The Cascade also allows you to control the flow with a little knob on the top.
The unit’s aesthetic is a winner though; it has a very cool translucent-blue plastic. Having a translucent media compartment is helpful because it allows the user to see into the filter and spot any potential clogging issues before they go too far!
The filter gets its name from a neat cascade design in the filter’s return. Penn Plax have implemented a zig-zag groove pattern in the return. Competitors generally have smooth returns which provide little extra surface area for beneficial bacteria. Whereas the Cascade’s ridges provide additional surface area for bacteria to colonize.
MarineLand Penguin Bio Wheel
The Penguin is super neat because it has bio wheels! The bio wheel provides excellent biological filtration because it is a highly oxygenated environment. The constant spinning and agitation of the water as it goes through the bio wheel allows the water to absorb lots of oxygen. This is valuable because your beneficial bacteria will thrive in a highly oxygenated environment.
However, the bio wheels will slow and become clogged over time. So, unfortunately, they can be quite a high maintenance feature. But, to me, the extra attention they require is worth it for the super vigorous bacteria they house.
In addition to the bio wheels, MarineLand’s Penguin filters have a large submerged filter media compartment where you can place your biological filter media of choice.
Fluval’s AquaClear hang on the back filters are very popular in the aquarium hobby. Like the Penn Plax HOBs, Aquaclears have almost transparent filter media compartments. This allows the user to peek at the filter media inside to see if it is free from clogs or blockages.
Speaking of the filter media compartment, the AquaClear has a great one! Specifically, the size and shape of the media compartment is conducive to packing in filter media, i.e. it’s wider front to back.
But that isn’t the end of it, the filter media compartment also benefits from an easily removable plastic frame. Your filter media will rest inside this frame, therefore allowing it to be slid out and cleaned easily.
Hang On Back Tips
Don’t use the replaceable filter pads/cartridges.
Well, actually, use them if they come with it. But just don’t worry about rushing out to replace them with brand new ones.
The manufacturers might well recommend buying brand new pads on a regular basis, but the truth is it doesn’t make sense to do this. This is because the pads are colonized with your beneficial bacteria, when you throw them away, you also throw away a significant part of your bacteria colony!
Furthermore, filter media shouldn’t “wear out” but rather it should have a long lifespan. If filter media becomes clogged with detritus, no big deal! Instead of throwing it away, just rinse off the media in dechlorinated water to alleviate the clogs and then, naturally, put the media back in your filter!
Use all the space inside the filter! Specifically, this means you should be filling it up with filter media. If you want to go cheap, you can use broken down lava rock as this has a reasonably large surface area for beneficial bacteria. Or, if you’re ready to spend some money, you can buy some of the very high surface area commercial filter media.