5 Ways to Make Hang On Back Filter more Effective

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Hang-on-back (HOB) filters have become extremely popular, and it’s easy to see why. These filters are efficient, versatile, user-friendly, and reasonably priced! Better yet, these filters are suitable for most aquarium sizes, including nano-tanks.

A good HOB filter will maintain good water quality thanks to its excellent water-purifying system. Virtually all HOB filters are well-equipped to handle anything the fish throw at them.

That’s because these filters are designed to perform all types of filtration— mechanical, chemical, and biological. Talk about multitasking!

But did you know that you can make your trusted HOB filter work even better? It’s true! And in this article, I’ll teach you how.

Keep reading to discover useful tips to get the best out of your aquarium filter. After all, the water can never be too clean, even with a multifunctional HOB on hand.

Add a Pre-Filter Sponge to Intake

A pre-filter sponge, also known as an intake sponge, is one of the cheapest and easiest ways to improve your HOB’s performance. At first glance, there’s nothing special about it. It’s just a cylinder-shaped sponge with a small gap on one end.

You fit it onto the filter’s intake tube, et voilà— your HOB is supercharged and ready for work!

So, how does such a simple addition help your HOB perform better? Well, it provides three main advantages:

  • It provides extra surface area for beneficial bacteria
  • It contributes to mechanical filtration by catching up extra debris
  • It prevents large food or waste pieces from clogging up the filter

Intake sponges are porous, so they can trap and host a lot of nitrifying bacteria. They act as additional filter media for biological filtration. Your HOB filter already has ceramic rings for this purpose. But having one extra bio media won’t hurt.

Since the sponge sits on the intake tube, it aids in mechanical filtration as well. Some of the larger debris will stick onto it instead of being sucked up by the filter.

This makes your HOB’s job easier and extends the time you can go between filter cleanings. The HOB won’t get dirty as quickly. In the meantime, it will work more effectively.

An intake sponge’s most important advantage is the extra protection your filter gets. Large pieces of food, gravel and even tiny fish can sometimes travel up the intake tube. Inevitably, these large bits will clog or damage your filter.

The sponge serves as a sieve that only lets the smallest particles pass through. This can save your HOB motor and tubing from such accidents.

Use High-Quality Bio Filter Media

Your HOB might have come with a set of filter media you still use. But filter media such as cartridges and activated carbon pellets must be replaced on a regular basis. On the other hand, foam sponges and bio rings can be reused.

But it depends on the quality of the media in question. Poor-quality sponges break down quickly. Similarly, low-quality rings offer only a small surface area for bacteria.

They can also get clogged and require replacements.

Investing in higher-quality bio filter media will make your HOB more effective for longer. I highly recommend the Seachem Matrix or Eheim Pro lines if you’re looking for the best biological filter media.

Their products offer fantastic quality for a fair price.

– Seachem Matrix

Seachem Matrix offers exceptional biological filtration. These little pebbles can harbor both nitrifying and denitrifying bacteria, aiding in the removal of both ammonia AND nitrates in the tank.

Moreover, this media provides an incredible surface area of more than 700 sq meters per liter! That’s a lot of room for good bacteria to colonize.

These little pellets have tiny pores extending far beyond the surface, providing both internal and external surface area. The bacteria are safely guarded inside the pebbles so that you can rinse the media without worries.

The pebbles are made of a 100% inert material. They won’t break down or leach any minerals into the water, preventing unwanted spikes in pH or hardness.

– Eheim’s Substrat Pro

Eheim’s Substrat Pro is a similar product. This bio media is made out of an artificial sintered glass material. The media comes in the form of highly porous little balls. If you opt for this product, you’ll get an amazing 450 sq meters per liter of surface area.

Just like Seachem, Eheim’s media provides internal surface area, guarding the bacteria in case of filter cleaning. You get both increased biological filtration and extended use out of this medium!

Oh, and while we’re at it— don’t forget the filter media bag!

A good mesh bag will keep all your filter media neatly in one place for easy removal and rinsing. Filter media bags also come in handy for keeping your different media separate. For example, if you want to use bio media and activated carbon, these might mix together and create a mess.

Carbon pellets are especially troublesome because they’re small and sneaky. They can travel around in your filter or down the intake tube.

The filter bag can prevent this annoying occurrence and save you a lot of maintenance time. Besides, a fine mesh bag might even keep your bio media from clogging up too soon, thereby extending its durability.

Add Live Plants into the Filter Box

Here’s an idea that both looks good and helps your filter! You can add live plants into the filter box to boost biological filtration. You’ll still need bio media in the filter to handle most of the load in the tank.

But plants can improve the process. As you know, live plants can also consume some of the nitrites and waste by-products in the tank.

However, there are a few caveats worth knowing when trying this method:

– You should opt for emersed plants instead of fully aquatic ones

A fully-immersed plant might not handle the conditions in the filter very well. There will be a lot of movement, which can lead to tangling or torn leaves.

Furthermore, immersed plants will grow rapidly, possibly clogging the filter.

You want plants that grow upwards to avoid this issue. Some options to look into include Pothos, Heartleaf Philodendrons, and Peace Lilies.

These plants can grow outside the water as long as the roots are submerged. They’re pretty slow-growing too, so they won’t take over your filter by surprise.

– You must choose hardy plants

Again, not all plants can handle the high flow inside the filter. Most immersed plants aren’t a good match. Unfortunately, most emersed plants are also incompatible.

The majority of species are vulnerable to root rot in high humidity conditions. Again, Pothos, Philodendrons, and Peace Lilies are good options.

– Don’t displace the bio media when adding plants!

Remember, the plants are an addition to the filter media, not a replacement! Don’t take out rings to make room for the plant. This defeats the purpose and removes a lot of the beneficial bacteria in the filter.

You can trim the plant roots instead if you need extra room. Use the bio media in the filter to fix the plant in place.

Add Activated Carbon Media

Not all aquarists use activated carbon. Truth be told, this media doesn’t hugely impact water quality. Activated carbon doesn’t harbor bacteria to aid in biological filtration. It doesn’t do anything for mechanical filtration, either.

But it is helpful if you need chemical filtration. It’s a good safeguard to have, especially in medicated aquariums.

Activated carbon helps you maintain clean-looking water. If your water turns brown or yellow after introducing driftwood, for example, activated carbon can help with that! How does it work?

Activated carbon absorbs dissolved substances such as phenols and tannins (things that stain the water) and several chemical contaminants, including chlorine and fish medication.

Activated carbon is affordable and easy to find. You can buy cartridges in most pet shops as well as online. Just know that you’ll have to change the carbon media every two to four weeks to maintain maximum chemical filtration.

If you’ve never used activated carbon before, know that this filter media comes last when layering.

You’ll add the carbon after the bio media. Again, keeping the biological and chemical media in separate filter bags is best.

Use Filter Floss for Cristal Clear Water

We’re all fans of mechanical filtration. So, why not add one extra layer? Enter filter floss— a less-known but highly efficient filter add-on.

You can use it as a second sponge to double-filter any remaining debris in the water. Essentially, filter floss brings the same benefits as a regular filter sponge.

However, filter floss has denser fibers than most regular filter sponges. Thus, it traps even the finer detritus that might otherwise go through the sponge.

It’s very helpful if you like your aquarium water crystal clear.

Another great thing about filter floss is that it’s very easy to use. You don’t have to worry about finding the perfect fit for your filter. It can be always just cut into the right size as needed! You can place it virtually anywhere you want in the filter.

Place it first in the flow column, and it will catch any remaining debris that passes the intake sponge. It works best when used as the first layer before the other media.


HOB filters are highly effective and versatile. They make an excellent choice for aquariums of various sizes, including nano tanks.

The best part is that you can upgrade and modify your HOB filter in multiple ways to make it work even better.

If you want to increase mechanical filtration, you can opt for a pre-filter sponge, filter floss, and filter media bags.

These add-ons will protect your filter motor and the biological media, increasing your filter’s lifespan and effectiveness.

Speaking of biological media, the best thing you can do is to switch from regular to high-quality materials. High-end bio media offers more surface area and can harbor bacteria in deep crevices for added protection.

My top recommendations in this sense are Seachem Matrix or Eheim Substrat Pro.

Live plants like Pothos, Heartleaf Philodendrons, and Peace Lilies can also happily live inside the filter for bonus biological filtration. And don’t forget the last piece in the puzzle— chemical filtration.

If you need to get rid of yellow or brown-tinted water, activated carbon is your friend. Use this filter media to keep the water clear and free of chemical pollutants and staining compounds from driftwood and plants.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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