The needs of water quality discus


Why water is so important discus?

As with many aquatic species, discus the water is the living environment of fish. Like our air contains oxygen, CO2, nitrogen and other elements that influence their health status…

Water this "source of life" element is intimately related to our fish.

Also be aware that it is a very good solvent; This means, it has good abilities to dissolve many substances.

These include for example the gas (oxygen, CO2 etc.) mineral salts (Calcium, magnesium, sodium…) or even metals (lead, copper…)

And that we will complicate things somewhat; as these items (dissolved) in water discus can play an important role in physiology and even interact with each other.

Les discus sont originaires d’Amérique du sud…

2nd wild vivarium 2018 Discus friends show

The waters have seen these fish born in the wild are sweet (they contain few minerals), and acid (pH under 7), Heiko Bleher in his book the Bleher's discus vol. 1» measure e.g. North Victoria do Xingu in 2002 a pH of 6,5. A conductivity 21 microsiemens to a temperature of 28.5 ° C.

The discus is therefore adapted throughout its evolution to live in this type of environment.

Reading this, Numbers of you froncerons eyebrows in scratching his head ... "My discus do not live in such water parameters! And they are living very well!"

I totally agree with you, but I think that this fact remains interesting to hear.

2nd Pattern pigeon blood Nordic Discus Show 2018

Certainly the years of breeding and selections made our current "Pigeon Blood" and other "Turquoise Red" more tolerant with regard to water quality. It remains that this fish keeps its ancestral party requirements.

Furthermore, we must emphasize the made that man raises the discus since shortly (before the second world war) and that the real explosion of varieties we know not to start in the 1980s...

Also, it is undeniable that each fish species has requirements and tolerances of its own.

In comparison, the discus the tolerance range is smaller example a neon innesi.

The first parameters to know…

Test of water drops

KH, GH, water pH…

For the maintenance of breeding discus, a KH located between 2 and 4 with GH 4 to 7 German degrees are quite suitable.

Naturally, with such hardnesses, the pH of the aquarium should be neutral to acid (7 and less than 7).


With regard to nitrogen contents, the discus tolerates a few ad hoc deviations, but not the inconvenience I advise you not to go above 25 mg/L nitrates.

On this subject, I suggest you also check this Article dedicated to the nitrates present in the aquarium water.

The nitrates in the aquarium

For ammonia and nitrite, the zero values are imperative. Their presence is toxic to fish.

I also invite you to consult the article VETO Fish on ammonia toxicity in freshwater.

Neutralize Chloramine

The discus will be sensitive to the presence of pollutants in the water such as heavy metals, chloramines or other. I do not have specific data about their tolerances on this topic…

But it is important to neutralize these elements before changing water made with tap water; For this use a water conditioner.

The use of a water conditioner is strongly recommended .

I can not count the number of tap water users (unconditioned) with whom I could discuss and who one day came face to sudden deaths problems… after water change.

Rhythm of water changes?

With regard to the rate of change of water, it is generally advisable to renew 30% minimum volume of the aquarium once per week. (We are talking here of maintenance of discus in "community" tank and not growing tank.)

This frequency varies of course according of each case: Reproduction, growing, population of the aquarium etc.

Attention: it will keep in mind that these are the results of your water tests that indicate whether the volume and frequency of water changes are good.

(See also: Rearing and reproduction of the discus on video)

Discus and CO2: Attention danger

Dennerle CO2 diffuser

Some precautions to take if you broadcast CO2…

As I was pointing in the article on maintenance of the discus,  I urge you to check your diffusion of CO2 if you want to use for your plants.

A well calibrated electronic pH meter(!) or permanent CO2 controller like those offered by the company Dennerle are essential to avoid poisoning.

The diffusion of CO2 is often used to lower the pH of the water discus. You should remember that CO2 is beneficial to plants but that the discus appreciate that very little…

From 20 mg/L I noticed that some discus could be strongly unwell.

The water in the discus

IMPORTANT: la qualité de l’environnement de l’animal

As you seen, water is an essential element which determines the life and health of fish.

Ensure a good environment to your discus (ensure a good quality of water) will be the best of the prevention against disease.

Environmental stress is often the first stress that the discus faces. In a healthy environment, the body of the discus is able to fight alone against many pathogenic agents (of diseases).

Be regular in your interview to provide your discus a stable water in accordance to their needs.

Move out of the water needs of discus, This is the risk of exposure to a problem "x" or "y"..

So, you have just finished reading the 1st chapter ! Find the next article on the water parameters and their meanings. Pending, If you want, You can at any time post your comments or questions in the topic "comment" at the bottom page.

I invite you to read:  Discus, understand the main parameters of water

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About Author

Discus Breeder and Discus columnist, Yann Hoiret share on the website Fanatik-Discus his experience and passion for the King of aquariums. From 2014 He worked as a writer for the french magazine "AquaMag", the German magazines "Discus Live" and "Discus yearbook". He participated as an international judge in France Discus show 2014 and 2016 in Arvert, au Greek Discus Show 2014 in Athens, Discus Show in Paris Grigny 2015, 2017 and 2019, au FIDO concurso 2016, 2017 and 2018 Spain, au Nordic Discus Show 2018 Sweden, au France Discus Show 2018 Cognac, Discusvrienden the discus competition 2018, 2019, 2022 in the Netherlands.


  1. Jean-Pierre on

    Hello ,

    Thanks for this critical perspective, comparative and interesting.
    Actually , Stendker said that their Discus like in the tap water.
    Personally I bought the Discus Stendker years ago ( Cobalt , Red turquoise and Pigeon blood) beautiful , very sociable and which are reproduced but I have not managed to grow small (I was not there to feed).
    On the other hand , What would you recommend to prepare the water, When one is in Paris, so with an inadequate tap water for Discus?
    My reasoning, Unlike that of the vendor, was that the Discus lives naturally in freshwater at low carbonate hardness and acid pH, so that even if they support a water more hard, they prefer a closer environment from the original, the fact that physically, they are the product of an evolution to certain parameters .

    So I have always used the osmosis water and I've put salts Preis . The ground nevertheless gave a hardness GH higher than the output of the osmosis plant … the KH is almost zero , the conductivity there is 85 Microphones (but it was 350 a few months ago ) .

    I do not know too much how to stabilize the correct settings …

    I do not know what to think of Seachem and their products for Discus …

    I filter on Purigen, Matrix, pozzolan … but during changes , What should do to make the nitrogen cycle is not disturbed …

    How to replace the ground who was responsible in organic and mineral waste ?

  2. Yann Hoiret on

    Hello Jean-Pierre,

    Yes I am rather of the opinion… As I explained in the article, Although some varieties or strains to adapt well in "hard" water; It is preferable to maintain freshwater discus.
    If the water or you live is not good quality, There is indeed a solution in mineralizing water osmosis with mineral salts. Preis salts do fit the GH of water only, leaving the close KH 0. For this, in order to avoid pH falls, It must be very careful about the pace and volume of water change. This does not leave too much right to the error.
    You have otherwise mineral salts of Dennerle "osmosis remineral. + "who they will the GH but also the KH in a balanced way. If wish you to obtain a KH of 3 or 4 German degrees, It is thus possible with these mineral salts. You can find your retailer preferred reseller of the brand (Or ask their so that he commanded you).

    The American brand seachem sells excellent products… Those just mentioned are highly reputable addition Atlantic.

    To avoid disrupting your filtration, just observe your filter bacteria and do not forget that these are living, and that they enjoy little shocks. Clean your masses of filtration with water of your aquarium that ye shall then, and once the filter has been cleaned, Add a dose of bacteria of maintenance.

    So that your soil does not accumulate too much organic waste: use a Bell at each water change sand.

    Hoping to have answered your questions.


  3. Hello I would like to buy a couple of discus. I have an Aquarium of 180 litres.
    If it is pretty great for the couple I would then know how do you make water quality and its good parameters do not have worries.

  4. Goodnight yann,
    I'm installing a discus «Stendker» sandbox. My tap water has a KH of 5 and a GH of 6 at a ph of 7.3
    Can you advise me please?
    Thanks in advance I am of Alsace

  5. Hello,
    I would like to know: I have my nephew who has buy 5 Discus there 1 week. There 2 Discus who have fairly rapid breathing and properly dismissed gills.
    What treatment should he do ? He does not eat.

  6. Yann Hoiret on

    Hello Thierry,
    A priori, on the parameters you provide me, I do not worry.
    You could just lower the pH. But the discus by Jörg Stendker are renowned for their tolerances at the level of water hardness and pH.
    I advise you to control other parameters such as nitrates, phosphates, silicates etc…
    The three parameters that you give here are not sufficient indeed to tell you that this tap water is adequate for the discus.
    Also, I advise you whatever it is to prepare your water on the eve of its use. (Filtration fine/coal, water conditioner, heating)


  7. Yann Hoiret on

    Hello Romain,
    Your concern seeks a thorough case study. Should provide much more information on the water quality, history etc…
    Do you run in a batch at random.
    I suggest you ask this on the forum "Discus simply ' which has a section"infirmary"with a form to fill out to help you. Sign and complete this:

  8. Goodnight yann,
    Thanks for the advice. What do you see as Filtration fine/coal. For the installation of a UV sterilizer SLR 800 from Eheim; think you that this is a good idea??? (And the filter where do I place?)
    Thanks Yann and good evening

  9. Yann Hoiret on

    Hello Thierry,

    Sorry for the late reply! I went next to this message…
    For "fine/coal filtration" I was talking about the cartridges that you can place in a jar on your water network. You find in all good DIY stores.
    The UV sterilizer is not a requirement, but the Eheim SLR range is indeed of excellent quality. To adjust the volume of the aquarium at the outlet of the filter.


  10. Hello,
    I would like to discus and I just put water aquarium of 750 litres there are 10 days.
    Unfortunately for a week I have a lot of algae… What do I do??

  11. Yann Hoiret on

    Good evening,

    For this kind of problems, We must explore multiple tracks…

    The water quality, can be found for example in addition in addition to silicates, of nitrates and phosphates in the water…. Check that:.

    Lighting, by checking the quality of the tubes (Mark + age of the tubes), but also the duration of lighting.

    The location of the bin, which; placed in a too bright play accelerates the onset of algae.

    The presence of plants (sometimes difficult to keep up with the discus) competition long-term algae.

    So there is a big job of exploration…. Also be aware that a newly launched ferry is subject to the occurrence of algae. Is also nature that moved.


  12. Good evening,
    I send you this message user the Artemia, How to make a farm.
    I bought a strain of adult live Artemia.
    Thank you very much

  13. Hello,
    Here I find myself in a virtually hopeless case : I have a 350 liters and I live in Oregon. The pH in the valve outlet is not very high. I have in my tank 5 discus, 10 cardinalis and 6 Corydoras sterbai. Water is 28 ° c.. Since the beginning (2 years still in the tray) I am sur-infestée of cyanos.
    At the beginning, I was advised to redo my bin with a technical floor to stabilize the pH and parameters, to slightly acidify the water and thus curb the spread (It was horrible, really, at the end of 3 days they could see nothing through the windows). After one year, It is always like that, I had to invest in a sterilizer uv I plug a few hours per day. A little less than cyanos, but still not bad when even. My plants have ceased to grow since I put this technical ground (???).
    The rate of silicate is not alarming. Nitrates do not exceed 25-30 mg/L. However trace elements : Dummies. Phosphates : non. Iron : No one.
    My fish seem to suffer of acidosis (pH 5,8, and even if I do not change the water from 2 weeks is a little less), I lost lot of cardinalis and all my lemon tetras (they had contracted a weird disease species on which I have never found anything which gave them black points everywhere, gradually, then species of wounds lined with these black spots on the flanks, then they would die all one by one after a few weeks). My discus ended up contracting the disease of the holes and lose a little weight (they are currently in treatment). Only, My Corydoras sterbai readily do not appear to suffer from the situation.
    I always of the Cyanobacterium… I commend not plant for now, useless, They suffocate after a few days by the Cyanobacterium and although I was cleaning without stopping, she become stunted in all ways. When I recovering a little fertilizer (without phosphates) and iron, growth moved again for a few days, but not more than that.
    I wanted to put a small amount of co2 for plants, but in the light of the pH… not worth it. I wonder if it would be unwise to turn all plants, to replace the technical ground by a simple sand of Loire (with the bottom to drain pozzolan), and simply put water osmosis in boosting occasionally plants (the water is poor in elements for plants here).
    I've never had, in 20 years of fishkeeping, sick fish at this point, or aquarium which also goes wrong.
    I am passionate but on the point of giving up because this aquarium eventually ruin me. Can you help me ?
    Thanks in advance.

  14. Yann Hoiret on

    Hello Romain,

    Sorry for the delay of response… I was moving to France Discus Show…
    The easiest is to leave stage Artemia nauplii and grow to adult.
    Complete cycles is possible but requires a certain monitoring…
    Their livestock would require a full article I could do here on this short response…
    I advise you to browse the site forum "" which has a special section dedicated to the breeding of brine shrimp. 🙂


  15. Yann Hoiret on

    Hello Celine,

    Furthermore… Sorry for the delay…

    Yes I understand your worries… It is necessary to review all of your aquarium…
    You can proceed in various ways but need to review things point by point.

    Check your light source and I recommend the reading of this booklet from Dennerle:
    You will find good information. On the other hand, rely on plants to compete with algae is more difficult to achieve in a sandbox to discus.

    At the level of the water, should be limited to the maximum nitrate values, phosphate and silicate… Even if they are 'בסס '.. More elements are less measurable.

    For this: You can add a resin in the filter of the type "phosguard" of seachem (phosphates + silicates) AND/or condition your water with 100% water + mineral salts Dennerle (They have the advantage of GH and the KH at the same time!). I know several people who this has just (Because of elements present in the tap water….)

    Both energize your aquarium. (Why not use an oxydator…)

    For your illness, According to your description, I think it's parasites.

    In short, We must review the thing as a whole, reviewing the light (type, period, age of the tubes, quality of the brand etc etc….) + the water comes a good number of problems… (It must also be lower your nitrate + silicates)

    Review can also be maintenance in its entirety (volume and frequency of water changes)

    Good luck!


  16. Hello,
    I currently have a tray of 240 liters and I intend to go to an aquarium of 450 liters in a bit in order to get discus.
    My tap water has a kh of 8, a gh of 10 and a rather basic PH.
    When I mix the tap water with osmosis water, I get a KH of 4, a GH of 5 However my PH is still at the top of 7.
    By injecting CO2 (I'm less than 60 bubbles per minute) My PH isn't always down below 7.
    The NO2, NO3 and PO4 in my tap water are 0.
    Is it really better to decrease the PH of my water (for example by using reverse osmosis water and re-mineralizable, or even using other methods to decrease the PH) either finally PH is not very important to the time as the KH, GH and other settings are correct?

    Thanks for your help.

  17. Yann Hoiret on

    Hello Arnaud,

    It is true that many aquarists focus on the pH value of the aquarium water.

    Discus prefer acidic waters but the varieties of livestock are adapting quite well at near neutral pH.

    You might be tempted to inject more CO2 but I don't recommend it not because the discus are rather sensitive.

    The hardness of the water is for me an important criterion. And it is true that your discus show their plus colors in slightly acidic water.

    For this you can use the 'black cones' dennerle, peat (that v ambrer water…) or extracts from leaves of oak of the kind "pH minus" JBL or AMTRA brand.

    However be very careful because using two sources of acidifying (CO2 + other) can be dangerous and difficult to manage. (Because it is not known if the pH will drop because of CO2 which can be toxic; or because the second source of acid)

    Limit your diffusion of CO2 and especially, check this with at least a permanent CO2 testing.


  18. Amaury.D on

    Hello Mr Hoiret,

    Very good article!
    When you talk to condition tap water with such aquasafe, you treat just the tap water or the mixture of water-tap RO?
    A big thank-you

  19. Yann Hoiret on

    Good evening,

    We could only handle the volume of water that target this kind of product. Namely tap water.
    The reverse osmosis having already stopped most unwanted elements present in water.


  20. Good evening.
    I wish I put myself in discus.
    I have a 600L tank and I intend to acquire sub adult specimens.
    How can I put volume 5 or 6 specimens to make them grow and then put in 600l?
    I intend to remain bare ground without water tank osmosis re-mineralized salt in preis. My kh will be close to zero but I wonder whether it is not better to put a raised floor to buffer the KH and stabilize the pH.
    I am taking your advice.
    Bravo for your videos
    Kind regards, romain

  21. Yann Hoiret on

    Hello Romain,

    beautiful project…
    For the magnification, a tank 250-300 liters of water will do. Emphasize the bare tank which will be much easier to maintain. The technical floor is to use that to create well-planted tanks.
    It will be tedious to maintain magnification tray discus and does not really fit with the objectives that you give…
    For your water, I rather privilégierai the Dennerle minerals that adjusts balanced KH and GH. Less risk for your pH and complete. You can give yourself a goal KH around the 3-4.
    Equip yourself a conductivity meter, that simplify the task for making your water…

    And thank you for your support, it makes me think that I must return! (Working on my videos…)


  22. Romain Schreiner on

    Thank you for your full and accurate response.
    Kind regards,

  23. Christian on

    Hello yann congratulations for this forum.

    Here I am preparing a corner aquarium 350 liters for discus; I live on the 1st floor and in the attic I installed a water filter in 3 steps: Sediment filter, granulated activated carbon block + two membrane reverse osmosis unit 100 ro equipped as standard as well as 3 filter cartridges.
    A very fine sediment cartridge (5one), a carbon foam cartridge and a granular activated carbon cartridge + pump boosters and TDS debit 400 L/D.

    I have a barrel of 150 liters that I re-mineralize with mineral salts and I want to change 100 liters per week by drip. In the aquarium I installed an overflow; See l'aquarium and encore.

    What do you think of the drip system??

    To prepare the water in the barrel, do I need to add a bubbler and a heater???

    What do you think of this project??
    Thanks see you soon

  24. Yann Hoiret on

    Good evening Christian, and sorry for the late response, I did not see him…
    Your project seems rather coherent to me.
    You can actually add heating and light bubbling in order to homogenize the temperature of the water and dissolve your mineral salts more quickly..
    Take care!

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