Whats the best discus Aquarium FILTRATION?

There are hundreds of choices but for a Discus fish tank, the bigger the better. The aquarium filters will keep your water healthy and your fish alive.  

IMPORTANT - I cannot recommend enough that you research the nitrogen cycle and learn how to cycle an aquarium correctly. You should be aware of this process if you are considering keeping any kind of fish. This will help you understand the processes that are going on in your tank and how to fix certain issues that will arise. Almost all issues are down to water quality. Water quality is controlled by the stock level, aquarium filtration, feeding and maintenance routine of the tank. Short falls in any of these aspects will only effect your fish and problems will start.

NOTE - You need more than good just good filters to maintain fish health. An aquarium is a closed system where living things are eating, and excreting. Filters will maintain the water but new water must be added at the required volumes and regular intervals to keep the fish in the best health. Water changes also help to control bacteria and parasite levels.  Water quality keeps your fish healthy and their immune response good, so their ability to deal with bacteria and parasites is improved. 

Also, we are now pumping water around at volume, constantly, 24/7, all filters make a noise, in a cabinet this is almost negligible with some filters. But there will be noise, surface noise, motor noise, water noises.  Consider where your tank is and what level of noise the household can live with.  Or your beautiful fish tank wont be popular for long.
 

FILTER CHOICES
First choice is a sump.  Or if you've bought your tank without a sump you're probably going to need some canister filters.  The filter needs to be sized for the tank, thats why internals are usually too small, unless you are planning to change so much water you dont rely fully on your filter for any length of time.

The volume of the tank and the number of fish you want to keep will determine the size you need. But you can never go wrong over doing the filtration. The only issue this will give you is with flow. Bigger filters have a higher flow and some say Discus fish generally do not like fast flowing water. Im not sure this is too much of an issue. However, bigger filters need cleaning less, contain more media and are therefore more effective. And there is many ways to get round and sort out the flow issues if you feel your fish are bothered by it. If you do not have enough aquarium filtration you will never keep your water at a suitable quality. 

Some canisters will include a heating element but that is usually at the expense of filter volume.  The more media, the more beneficial bacteria, the better your water. So go for the largest you can. Some brands are better than others and this usually follows the "you get what you pay for" rule. Cheaper tends to not last and problems will occur. Remember an external canister filter is taking the water out of your aquarium and pumping it back several times per hour. There is an amount of water pressure to contain so you need good quality seals and joints. Any leaks or issues quickly become big problems.  

A sumped tank has an overflow that the water goes over to fall into the sump. The sump part is essentially another tank under the main aquarium. It is divided into sections and the water flows through the sump and any media placed in it. Its then pumped back up into the tank where it overflows back down and so the process continues circulating the water through the tank and the sump. If the pump fails the sump should be large enough to contain the excess water until it can no longer overflow, so if levels are set correctly it should never have a leak/overflow issue. 

I've never had a sumped tank but wish I did.  I always wondered how noisy they might be but the benefits of the extra volume of water and the easy access to the media must make cleaning very easy.  There is far more room for media, something which you can never have enough of.  You can also put the heaters and other accessories in the sump so they will not be on view in the main tank. The overflows are also well hidden so there is many benefits to a sumped set up and you could say this is the best way to run a tank for these fish. If you want the very best filtration with the most flexibility for positioning accessories and additional media this is definitely the way to go. 

Although not strictly a filter a UV sterilizer is usually connected to the output of a filter or pump.  Your canister filter is sifting debris out of the water, microorganisms can survive this process and remain in the water.  A UV sterilizer passes the aquarium water through a crystal sleeve where it passes a high-intensity ultraviolet light.  This exposes any free floating microorganisms to a lethal dose of UV radiation.  Various things happen to microorganisms on exposure to UV, the UV sterilizer basically kills of anything passing the UV source.  Thus removing any free floating microorganisms, microalgae, parasites, bacteria and so that are unfortunate enough to pass by the UV source for long enough.

Its a great addition to a system to reduce the levels of unwanted organisms in your water.  It can help water clarity and as the name suggests it does clean your water.

Exposure time is important so follow the guidelines on your UV sterilizer.  Most have a max flow rate. The longer the organisms are exposed to the UV source the more chance they will be rendered ineffective.  So slow flow is best.

TOP TIP - Change the UV bulb regularly, most units have safety cut outs but never activate a UV bulb if its is not covered by its enclosure.