The Aquarium Sump Filter

So exactly what is a sump filter? Well a sump filter is nothing more than a large container or reciprocal that sits outside of your tank and contains not only extra water, but also all your filtration material and often heaters, skimmers etc. Sump filters can be manufactured from any basic material such as glass, acrylic or plastic. In fact, many people who use sump filters make them themselves, they are available commercially but they often cost a lot of money. Sump filters are normally used on saltwater aquariums where water quality is really very important indeed. However, people have now started using sump filters on large freshwater aquariums that contain very large fish. Because water quality is so important in an aquatic environment, extremely efficient filtration is absolutely paramount. Even though a sump filter is quite basic and often very crudely put together, they are arguably the most efficient filtration system you can install on an aquarium. A large sump filter can contain enormous amounts of media, far more than you would ever be able to fit into a commercially available filter. So it makes sense to use a sump filter if you are intending on setting up an aquarium that may contain several hundred gallons of water.

So we've discussed what a sump filter is, we now need to talk about how we set it up and what is needed for a freshwater aquarium. If you do a search on the Internet you'll probably find that the majority of "sump filter" information relates directly to marine tank setups, i.e. saltwater aquariums. The majority of the information relating to saltwater is not going to benefit you if you are keeping a freshwater tank because marine fish keepers often use specialist equipment and media. For instance, protein skimmers although used extensively on saltwater aquariums are absolutely not necessarily on a freshwater aquarium. Many marine enthusiasts use specialised media such as "mud" yes, mud. Mud is not the sort of media us cichlids keepers would ever use in our filters.

If you decide a sump filter is something you want on your aquarium then you will need to work out exactly where it is going to go. If you search the Internet and YouTube then the majority of sump filters will be located directly underneath the aquarium. There is no rule of thumb that states that the filter has to be located in this position, you can put your sump anywhere you want as long as the water flows easily from the aquarium and then back again. My sump filter for instance is located next to my aquarium. I used to have the sump located in the cabinet underneath the aquarium but I personally found that when it came to maintenance, it was actually quite difficult to clean the sump when it was tucked away in the cabinet.

The next thing you need to do is decide how big your sump is going to be. I would recommend that your sump filter be no smaller than a quarter of the size of your aquarium, i.e. if your aquarium is 300 gallons then the sump filter should be 75 gallons. However, there is nothing wrong with going bigger than this, in my opinion the bigger the better. As for what your sump is constructed of, acrylic, glass or plastic is readily available and is easy to work with. You could start from scratch and build the sump, however it's probably easier to start off with an old aquarium, or in my case a plastic water tank.

The next step is how you partition your sump. This basically means dividing your filter into chambers that will house the different types of media, plus equipment such as heaters and pumps. Everybody does it different, there are no set rules about how many chambers you must have and what shape they need to be. A sump without any partitioning would still work as long as you have media that your aquarium water comes in contact with and then gets returned back to the aquarium. Having said this, an efficient and properly designed sump filter should at least have a few chambers that can be utilised to hold different elements.

A simple and efficient sump filter would have the water entering the first chamber which could either be left empty or contain some media, the choice is yours. The second chamber is where you would place the majority of your biological media. The third chamber would contain pumps and heaters. Let's have another look at the chambers and what could be placed in them. If you are keeping large cichlids then you will already know that they produce an enormous amount of waste. Don't skimp on your mechanical filtration, use as much as you deem necessary. My advice would be to use it in more than one chamber, and use different grades of mechanical filtration as well. The whole point of using mechanical filtration is to collect solid waste such as fish poo and uneaten food. Mechanical filtration is very easy to clean, you basically just rinse it out in water. If you don't use enough mechanical filtration then all the crap which ends up as a horrible sludge starts building up in your biological filtration, you've then got the hassle of taking it all out to clean. You're never going to stop all of the dirt getting through, but if you use a decent bit of a mechanical filtration you can certainly catch a lot of it before it gets through. Try and avoid using very fine polishing type mechanical media because this type of material will become clogged with dirt very quickly. Of course if you don't mind cleaning your media once a week then you could use very fine media that would remove even the tiniest of particles, but personally it's more trouble than it's worth because once mechanical filtration becomes clogged with dirt, the water cannot pass through the sponges quickly enough and the water will start backing up, this is where you will find water flowing everywhere instead of where it is supposed to go inside your sump.

The core of any filter is the biological media, this is what removes all the toxins and horrible nasties from the water and keep your fish alive and healthy. There is so much biological filter available we would be here until next Christmas discussing it. The best advice I can give you is to go for the largest biological media you can find. You want to use media that has a large surface area for bacteria to grow on. I would recommend bio balls as these are slightly smaller than ping-pong balls but are covered in lots of little prongs that are just ideal for bacteria growth. Bio balls come in bags of about 1000, more than enough for a large aquarium and at a very reasonable price as well. The beauty of using this type of media is they will last for absolute years, in fact you will probably never have to change them as they don't have a tendency to become very dirty, in fact when you look at them you would never believe that they are covered in millions of bacteria. If you want you can also put in another type of biological media, I've got a large bag of Alfagrog in my filter as it has a very porous surface which is ideal for bacteria growth as well.

Another bit of useful advice would be to use media bags inside your sump filter. This basically means that  instead of having to scoop media out by the handful, the media is contained in a bag which just needs to be lifted out in one go. My philosophy is if you're going to go to the extent of installing one of these filters then do it properly and make life as easy as you can for yourself. Finally, if you really want to make your sump efficient when it comes to cleaning, you could put some outlets on it so that you basically attach a tube, open the taps and then drain all the crap out from the bottom.

A sump filter is definitely the way to go if you are going to set up a large aquarium containing lots of big fish. Commercially available canister filters will work, but they will become dirty very quickly, you will also need more than one filter if you have a big tank, these filters don't come cheap. For a fraction of the price of a large canister filter, you could set up a large sump filter that will completely blow any commercial filter out of the water when it comes to efficiency.