Some hobbyists have a sump, while others prefer to use a sump. Many have never heard of aquarium sumps and refugiums, and may be wondering which is the best option for their setup. But did you know that the best option for maximum filtration system performance is to install both?
So how does a shelter work and what is the difference between the two? Read our guide on Shelter vs. Sinkhole and you’ll learn everything you need to know!
What is an aquarium shelter and how does it work?
An aquarium shelter can be used with cold, tropical, fresh, brackish and salt water tanks. It is basically a separate sump that shares the same water supply as the main display tank.
A shelter is defined as a “ shelter ” that can come in the form of an external box that lives out of sight in your aquarium cabinet, as an inconspicuous unit to hang on the back, or in plain sight in the aquarium itself. Additionally, some aquarists create a mini refugium by using a dedicated box compartment in their sump or by purchasing a small aquarium for that purpose.
Hobbyists use shelters for many different reasons:
- A facility for growing natural food for fish, such as copepods, that would not survive in the main tank.
- A place to grow algae that can work for you by extracting nitrates and waste from the tank water, helping to keep the water safe for your fish.
- A place to store living sand or shelter mud that absorbs nutrients from the water and helps grow certain species of algae.
- A dark “cryptic zone” where live sponges can be grown as natural filters for reef tanks.
- Grow corals in a safe environment that is well away from coral-eating fish species.
Within the shelter environment, you can keep creatures that would not survive in the main tank or detract from its aesthetic appeal. You can also grow organisms that help filter and clean the aquarium water, increasing the efficiency of your biological filtration system.
In some tanks, the flow of water is restricted to accommodate the fish or creatures that live in the aquarium. Within the separate shelter environment, flow can be boosted, if necessary, to promote plant growth or enhance biological filtration.
Additionally, the light cycle within the shelter can be set to the opposite side from the interior of the main display tank. During the “daylight” hours of the shelter, the plants extract the CO2 that forms acid during photosynthesis, which helps keep the pH of the water more stable. Bright lighting within the shelter can also be helpful in encouraging the growth of useful species of algae that would be unsightly within the main tank.
What is an aquarium sump?
By definition, a sump is a reservoir or pit that acts as a drain or container for liquids and is usually the lowest point in a drainage or circulation system.
An aquarium sump is an additional tank that typically lives below the main display aquarium and is used to house equipment such as filters, heaters, protein skimmers, and associated cables and hoses.
The sump is also used to add water volume to the aquarium system, helping to keep the water clean and alleviating the problem of nitrate buildup. Most hobbyists prefer to use drip filters with a sump so that the water passes through the filter tower before falling into the sump.
There are commercially produced acrylic sumps available, or you can simply recycle an old aquarium for that purpose.
What are the advantages of using a sink?
One of the main benefits of using a sump is that it allows you to organize and consolidate several standard fish tank hardware items all in one place. That makes maintaining your setup so much easier and keeps what would otherwise be an unsightly mess out of sight so it doesn’t detract from your aquarium display. If the sump is large enough, you can use it to add additional filter media, a UV sterilizer, or a filter sock.
You can also use a sump as a mechanism for the delivery of carefully dosed fish medications, plant fertilizers, top-up water and the like to your system without the risk of disturbing your livestock. Problem fish can be temporarily housed in the sump, and you can also use the space to farm shards for reef tanks.
A sump also maintains a stable waterline in the main tank and keeps the water surface free of contaminants. Also, if you run a system that has pipes coming out of the aquarium, carrying water to filters and other equipment in the sump, the sump collects the water and prevents it from overflowing.
Is a refuge the same as a sinkhole?
Therefore, it may appear that a refuge is actually a kind of sinkhole. However, there are several differences:
|Can be used with salt, fresh and brackish water tanks||Can be used with salt, fresh and brackish water tanks|
|Multiple uses||Primarily an equipment storage facility|
|Can act as additional biological filter system||Contains filtration equipment|
|Relatively quiet operation||Relatively quiet operation|
|It can be used to house certain plants, live foods, macroalgae, etc.||Allows customization of the equipment configuration.|
|Planted refuges can help stabilize the pH of the aquarium||Not suitable for house plants due to lack of space and light.|
|The lighting can work independently of the main tank.||No installation for lighting|
|Can be used to increase the volume of water in the main tank||Can be used to increase the volume of water in the main tank|
The best of both worlds?
So you can see that there are actually some very good reasons to keep a shelter and sink.
But do you place the shelter before the sink or vice versa? That depends on your setup.
For example, if you have a display tank that relies heavily on effective biological filtration, I would recommend installing the shelter downstream of the sump. That way the water will be full of nitrate but devoid of oxygen before it enters the refuge from the sump and biofilter.
However, if you have a saltwater reef aquarium, you may want to place the refugium before the sump. With that location, all of the yellowish compounds released by the algae in the refugium will be removed by the chemical filtration media in the sump before the water is pumped back to the main tank.
Shelters and sumps can be used with fresh, salt and brackish water tanks. Sumps are primarily used for storage of system equipment items and can allow hobbyists to customize their filtration setup. Shelters are a bit more versatile and can be used to improve biological filtration, raise live food, grow plants, and more.
I hope you’ve enjoyed our comparative guide to shelters and sinkholes. If there is anything else you need to know, please write your questions in the comment box below and don’t forget to share the article with your friends if you find it useful.