Sump Filters: Advantages, Disadvantages, and Best Practices

Is a Sump Filter Worth the Effort for Your Aquarium Setup?

If you have a single tank or a combination of tanks that totals 100 gallons (about 454 liters, or 120 US gallons) or more, installing a sump filter can be a valuable addition - provided that you can connect your tanks to it. This usually requires drilling the glass to accommodate piping, which might not be feasible in an already established setup. For example, I’m considering adding a sump to my living room display, where I have six tanks positioned along two walls. However, to do this, I would need to empty each tank, drill a hole in the bottom for the pipe connector, and then set the tank back up. Additionally, I’d have to install piping to direct water from the tanks to the sump and then back into the tanks at the top.

So why bother?

Each of these six tanks needs regular water changes, and conditions can fluctuate more rapidly in individual tanks. Each tank also requires its own filter, heater, and air supply for ornaments and other equipment. By connecting all these tanks to a single sump filter, water changes become much easier since you’ll only need to manage one system. Water conditions will be more stable across all tanks, and heating will be more efficient. Additionally, the inlet from the sump will create a strong current in the tanks, something that an under-gravel filter (UGF) doesn’t provide.

Fortunately, when I built the shelf to hold the tanks, I anticipated this possibility and included hidden areas where I could run piping if I decided to make the change. For me, the conversion isn’t as challenging, but for other setups, it may be more difficult to implement.

What are the Benefits of a Sump Compared to a Canister or HOB Filter?

1. Volume:

   Canister and HOB filters are limited to handling a specific volume of water. In contrast, a sump’s capacity is only limited by the size of the pipes you install and the power of the pump you use.

2. Flexibility:

   A sump offers complete flexibility in the type of media you use. You can choose from gravel, beads, ceramics, floss, foam, or almost any other media. It can also house activated carbon, heaters, and other accessories, depending on its size. Just be cautious not to use media that might restrict water flow too much!

3. Efficiency:

   Since you control the choice of media, you also control the filter’s efficiency.

4. Stocking Levels:

   A sump increases the total volume of water in your system, allowing you to safely stock your tanks at higher levels without overcrowding. For example, a 100-gallon (approximately 454 liters, 120 US gallons) tank connected to a 30-gallon (approximately 136 liters, 36 US gallons) sump effectively gives your fish 130 gallons (approximately 590 liters, 156 US gallons) of water. This means you can increase your stock levels by about 30% without risking overstocking.

5. Stability:

   Maintaining water quality is easier in a larger water system than in a smaller one. Fish waste is more diluted in a larger volume of water, so it’s beneficial to make your system as large as possible.

However, as with anything, there are some drawbacks. Here are a few I have encountered or anticipate:

1. Leaks:

   Like any plumbing system, a sump is susceptible to leaks. The more piping you have, the higher the chance of water escaping.

2. Flooding:

   With more water in the system, a significant leak could release a large amount of water. Additionally, if the sump isn’t set up correctly, a power outage could cause flooding if water from the tanks above overflows the sump’s capacity. You might also experience siphoning issues if the inlet is below the water level during normal operation. It’s worth considering a control valve during the planning stage to prevent this.

3. Disease:

   If a disease enters the system, it can spread to all connected tanks, making it costly to treat. This underscores the importance of maintaining optimal water quality at all times and quarantining new fish before introducing them to the system. Including UV sterilization in the setup is also a good idea.

Conclusion:

Sumps can be a valuable tool for aquarists when the right conditions are met. If you're planning a large aquarium, a sump is definitely worth considering. It can also be beneficial if you have multiple tanks in the same location. For those building a fish house or a breeding rack, a sump should be a strong contender in your setup plans.

However, it's crucial to follow some guidelines regarding the size of the sump in relation to the water system it manages. You need to ensure there is enough capacity in the sump to handle any backflow during a power outage. The difference between the operating and settling levels is influenced by the water flow rate from the sump to the tank - the faster the flow, the higher the operating level, which means more water needs to be accommodated during settling!

Questions and Answers

Feel free to submit your own questions about sump filters, but please ensure they are unique and haven't already been addressed on this page. Initially, we published questions at aqua-fish.net/answers, but we've since integrated them with related articles. Here are two common questions:

What size sump do I need for a 100-gallon tank?

Answer: For my 100-gallon (approximately 454 liters, 120 US gallons) tank, I'm using a 36” (approximately 91 cm) sump that is 18” (approximately 45 cm) deep. The key factor is how efficiently the sump is divided into compartments for the pump, media, etc. I created three chambers, allowing me to add a Deep Sand Bed in the second chamber for enhanced filtration.

What media should I use in a sump?

Answer: In the first chamber, sponges are ideal for mechanical filtration. A Deep Sand Bed is the only additional media you need, unless you want to include a phosphate remover.