Hang On Back Filter: The Complete Guide for Aquarium Enthusiasts

Aquarium keeping is one of the most rewarding hobbies, but maintaining a healthy and clean aquatic environment requires the right filtration system. Among the various types of filters available, the Hang On Back Filter (HOB Filter) stands out as one of the most popular choices for beginner and experienced aquarists alike. Known for its ease of use, affordability, and effectiveness, the hang on back filter has become a staple in freshwater and saltwater aquariums.

In this guide, we’ll dive deep into everything you need to know about hang on back filters — how they work, their advantages, how to set them up, and the best ways to maintain them. Whether you are new to the hobby or looking to optimize your existing setup, this article will provide you with a complete understanding of HOB filters.

What Is a Hang On Back Filter?

A Hang On Back Filter (commonly abbreviated as HOB filter) is a type of external filter designed to hang on the rear wall of an aquarium. Water is drawn up from the tank through an intake tube, passes through different filtration media inside the filter chamber, and is returned to the aquarium as clean, oxygenated water.

HOB filters are widely appreciated because they combine mechanical, chemical, and biological filtration in a compact and easy-to-use design. Unlike internal filters that take up tank space or canister filters that require more effort to set up, HOB filters provide a convenient balance of performance and simplicity.

How Does a Hang On Back Filter Work?

The working principle of a hang on back filter is straightforward:

1. Water Intake – An intake tube extends from the filter into the tank and uses an impeller to draw water upward.
2. Filtration Stages – The water flows through various filter media:
   • Mechanical Filtration: Sponges or filter pads trap debris and solid waste.
   • Chemical Filtration: Activated carbon or specialized media remove toxins, odors, and discoloration.
   • Biological Filtration: Bio-rings or ceramic media house beneficial bacteria that break down ammonia and nitrites.
3. Water Return – The clean, filtered water is released back into the tank, often creating a small waterfall effect that helps aerate the aquarium.

This combination of filtration ensures that water clarity, toxin removal, and biological stability are maintained.

Advantages of a Hang On Back Filter

HOB filters are popular for many reasons, making them one of the most recommended options for hobbyists. Here are their key benefits:

1. Easy Installation

Unlike canister filters that require complicated plumbing, a hang on back filter simply hangs on the back of the tank and plugs into an outlet.

2. Space-Saving Design

Since it hangs outside the aquarium, it doesn’t take up much room inside the tank, leaving more space for fish and decorations.

3. Versatile Filtration

Most HOB filters include slots for multiple filter media, allowing for mechanical, chemical, and biological filtration.

4. Affordable

HOB filters are generally more budget-friendly than canister filters while still offering excellent performance.

5. Easy Maintenance

Changing cartridges or cleaning the filter media is simple and can be done without dismantling the entire system.

6. Oxygenation Benefits

The water return creates surface agitation, which promotes gas exchange and helps maintain oxygen levels in the aquarium.

Choosing the Right Hang On Back Filter

When selecting a HOB filter, consider the following factors:

1. Tank Size Compatibility – Always check the filter’s gallon-per-hour (GPH) rating and ensure it matches or exceeds your aquarium size.
2. Flow Rate Adjustability – Some models allow you to adjust the water flow, which is useful for delicate species like bettas or shrimp.
3. Filter Media Customization – Look for filters that let you use your own media instead of being restricted to proprietary cartridges.
4. Noise Level – Some filters are quieter than others, making them ideal for aquariums in bedrooms or offices.
5. Durability and Brand Reputation – Popular brands like AquaClear, Fluval, Marineland, and Seachem Tidal are known for reliability.

Step-by-Step Guide: Setting Up a Hang On Back Filter

Setting up a HOB filter is quick and easy. Follow these steps:

1. Unpack and Rinse Media – Remove the filter from the box and rinse all media with dechlorinated water.
2. Assemble the Intake Tube – Attach the intake tube securely to the filter.
3. Prime the Filter – Fill the filter box with aquarium water to help the impeller start smoothly.
4. Hang on the Back of Tank – Place the filter on the back wall of your aquarium.
5. Plug It In – Connect it to power, and the filter should start pulling water immediately.
6. Check Flow – Ensure water is flowing evenly through the filter and returning to the tank.

Maintenance Tips for Hang On Back Filters

To keep your filter running effectively, regular maintenance is essential.

• Weekly: Check the water flow and clean any debris from the intake tube.
• Bi-Weekly: Rinse the mechanical filter media (sponges or pads) in tank water to avoid killing beneficial bacteria.
• Monthly: Replace or recharge chemical media like activated carbon.
• Every 2–3 Months: Deep-clean the impeller and housing to remove algae or buildup.

Never clean all media at once; stagger cleaning to maintain beneficial bacteria populations.

Common Problems with HOB Filters and Solutions

1. Filter Not Starting After Cleaning – Ensure the chamber is primed with water before plugging it in.
2. Reduced Flow Rate – Clean or replace clogged filter media and check the impeller.
3. Noisy Operation – Air bubbles or debris in the impeller can cause noise; clean thoroughly and ensure proper installation.
4. Water Overflowing – Dirty or blocked media may cause overflow; rinse or replace filter pads.

Best Aquarium Setups for HOB Filters

Hang on back filters are suitable for:

• Freshwater Aquariums – Perfect for community tanks, planted tanks, and beginner setups.
• Saltwater Aquariums – Can be used for smaller marine tanks with live rock and protein skimmers.
• Betta Tanks – With adjustable flow models, they provide gentle filtration.
• Nano Tanks – Compact HOB filters fit well on small aquariums.

Hang On Back Filter vs. Other Filtration Systems

• HOB vs. Canister Filters – Canister filters are stronger and better for large tanks, but HOB filters are easier to set up and maintain.
• HOB vs. Sponge Filters – Sponge filters are cheaper and good for breeding tanks, but HOB filters offer better water clarity.
• HOB vs. Internal Filters – Internal filters take up space inside the tank, while HOB filters remain external.

Conclusion

A hang on back filter is one of the most practical, affordable, and reliable filtration systems for aquariums of all sizes. Its ease of installation, versatility in filtration, and low maintenance make it an ideal choice for beginners and experienced hobbyists. Whether you have a freshwater community tank, a planted aquarium, or even a small saltwater setup, a HOB filter can keep your water clean and your fish thriving.

Investing in the right filter is investing in the health of your aquatic ecosystem — and for many aquarists, the hang on back filter is the perfect balance between efficiency and simplicity.

FAQs About Hang On Back Filters

1. What size hang on back filter do I need?
Choose a filter rated for at least the size of your tank. Ideally, pick a model with a flow rate 4–6 times your tank’s volume per hour.

2. How often should I clean my hang on back filter?
Light maintenance should be done weekly, but deep cleaning and media replacement are usually needed every 4–6 weeks.

3. Can I use a HOB filter for saltwater aquariums?
Yes, but they are better suited for smaller marine tanks. For larger saltwater tanks, canister filters or sump systems are recommended.

4. Do I have to use the cartridges that come with the filter?
Not always. Many HOB filters allow you to use your own filter media like sponges, bio-rings, and activated carbon.

5. Are hang on back filters noisy?
Most models operate quietly, but noise can occur if the water level is too low or if debris is stuck in the impeller.

6. Can I run a HOB filter on a planted tank?
Yes, they work well in planted tanks. Just ensure the flow rate isn’t too strong for delicate plants.

7. Do hang on back filters provide enough oxygen for fish?
Yes, the water return creates surface agitation that helps oxygenate the water.