Water for discus fish
When keeping discus fish the main thing that you really have to carry about is quality of water because poor quality water can cause discus fish diseases. High quality of water I call when there are no toxins such as nitrite, phosphate, ammonia, etc in it. Also very important thing is pH which should be between 5 - 6,5 and dH (water hardness) which should be 3-15 degrees. Temperature of water for discus fish should be about 82 – 86 degrees of Fahrenheit (28-30 degrees of Celsius).
To check parameters of water you should have some tests. You should have at least the tests which can check five or six water parameters at once. These tests usually are plastic stripes with indicators on it and they are cheap. I recommend JBL tests because they are accurate enough. Of course the best thing is to buy serious tests which are very accurate but its price is higher.
Firstly you should check water parameters of the water which is at your home. Sometimes the water can be just perfect and you don’t need to do anything with it but sometimes it requires some modifications. Also keep in mind that in some parts of the world they still add chlorine to the water. You should find out if the water in your home is with chlorine or not. If chlorine is added to the water you use than you should keep the water in some tank and wait few days when it will lose this toxin and only then it will be ready for your discus fish aquarium.
Water hardness is the sum combination of noncarbonated and carbonates hardness of your water. As I mentioned before it is measure as dH. Kh is the levels of carbonates of magnesium and calcium.
Filtration
Filtration is one of the most important things that helps to keep high quality water. Without filtration is nearly impossible to keep discus fish or any other fish.
Mechanical filtration
The main goal of mechanical filtration in your discus fish aquarium is to remove large parts of plants or uneaten food. I recommend using sponge in mechanical filtration because it can keep the dirt pretty good. The sponge should be washed from time to time.
Biological filtration
Biological filtration doesn’t remove large parts of plants or uneaten food like mechanical filtration does but it reduces one toxic material to another less toxic.
In your aquarium there is bacteria which is called nitrobacteria. It is one of those good bacteria which helps to keep your water’s quality. Nitrosomonas sp. bacteria consume the toxic ammonia that is produced by your discus fish. The ammonia is reduced to nitrite. The nitrite is consumed by Nitrobacter sp. and it is reduced to nitrate which is the least toxic.
This bacteria colonizes in all the surface of your aquarium also everywhere in a filtration system. If you have filtration with small ceramic tubes in one layer then I think you have sometime wondered how it can filtrate the water. These tubes are the shelter for nitrobacteria where it lives. So when washing filtration system you should always remember do this with the water from you aquarium. That’s because the water from a tap can be of different temperature that will affect this bacteria. Also it is said that you should not use water directly from a tap because the moving water can wash out nitrobacteria.
Chemical filtration
Many aquariums do quite well without chemical filtration. Frequent water changes helps to remove toxins from the water. But sometimes if for example the water from your tap has lot of toxins you should use chemical filtration. Activated carbon helps to remove many toxins, heavy metals and even medication after the discus fish treatment. But keep in mind that it can’t remove ammonia, nitrite or nitrate as biological filtration does.
Resins are like magnets which attracts substance such as nitrates. It is usually used in canister filters and when the water goes throw, it caches all the nitrates in it.
So that’s what I wanted to say about filtration and water for discus fish. Hope this will help you. By the way keep in mind that flow of water that makes your filters shouldn’t be very strong. Discus fish needs slow moving water like in its habitat.