Why do so many water changes?

[Braydon00]

Let me start by stating I fully agree and do change large amounts of water, minimum of 3X a week...(about 50-60%). Clean my canisters every 3 weeks, the 90 gal tank has about 900 gph filtration. My question is why do so many if 1) my water has 10ppm nitrates, 0 nitrites, 0 ammonia, and is crystal clear 2) has with a TDS of ~160 3) I use RODI water with tap since I have extremely hard water with pH of 8.4-8.6, after dilution pH is about 7.2 4) minimal algae if any? I read so many posts on here with people saying they change 75% everyday or every other day. In my mind if I'm not trying to breed and don't have fry there is no need to do such large wasteful water changes. I have 8 discus (juveniles ~4-4.5''). I should also state my tank is planted so they help with filtration as well. I'm not trying to start an argument, just trying to gain some knowledge from some very awesome people on here :).

[discuspaul]

It's been the experience of numerous long-time discus-keepers who have kept discus in planted environments with few, infrequent water changes that the build-up of uneaten food, fish wastes, decomposing plant matter, and other detritus, often results in the development of undesirable bacteria which can, and often does, become the cause of health issues in discus, poor growth results, and mortalities over time.
Discus do not tolerate poor water quality and conditions, which no amount of filtration can overcome, and only thrive with continuous large fresh, clean water changes.
That's the bottom line.

[afriend]

The main reason for frequent water exchange is to reduce dissolved organic compounds. DOCs come from two sources: uneaten food and feces. The organic compounds are not toxic. However there are bacteria in the tank that feed on the organic material and thus produce other compounds that are toxic. This process is common in nature and is evident by the foul smell of any organic material such as dead animals or decaying vegetation. Even if the uneaten food and feces are removed from the tank daily, the water can become saturated with DOCs and cause problems.

My understanding is that discus do not have a very robust immune system and this causes them to be very sensitive to unhealthy conditions.

[nc0gnet0]

My understanding is that discus do not have a very robust immune system and this causes them to be very sensitive to unhealthy conditions.

I am not so sure I would word it that way. I much prefer:

Discus live in warmer temperature waters in which bacteria thrive and multiply much faster than some of the other colder water tropical fish. Therefore increased water changes are necessary to keep the pathogen level low. Your point about Doc's is a good one, but I am not so sure I would categorize discus as having a weak immune system, but rather living in an environment that without proper care subjects them to higher than normal pathogen levels.

[DISCUS STU]

In nature Discus also come from brown water environments that are naturally low in ph. The low ph acts as a bactericide keeping bacteria and ammonia levels low. In an aquarium trying to keep ph at levels around low 6 or upper 5's is difficult to do successfully and can lead to dangerous ph crashes.

Maintaining aquarium water at the right ph will also require more water changes, as well as also to remove the pathogens to which Discus are sensitive. Bettas can live in almost anything, Discus have parameters for better health that aren't totally rigid, but they are higher maintenance fish than most others.

[YSS]

It's all about the bio-load of the tank. If you have high bio-load, then you will have to do more frequent water changes. I only do 50% weekly water changes on my tank with discus, but it's a relatively low bio-load tank.

[Larry Grenier]

Another BIG reason for all the water changes it that many folks here feed their fish an amount that many community fish keepers consider excessive. To offset the contaminants added thru rotting food, fish poopies... they do lots of water changes. That being said, there are others who have been successful with smaller water changes and large plant filters similar to what you have (10ppm nitrates).

[Braydon00]

This makes much more sense! I've been asking around and wasn't having much luck with an answer. Ill most likely up the water changes to every other day. Thanks for all the explanations guys!

[afriend]

I am not so sure I would word it that way. I much prefer:

Discus live in warmer temperature waters in which bacteria thrive and multiply much faster than some of the other colder water tropical fish. Therefore increased water changes are necessary to keep the pathogen level low. Your point about Doc's is a good one, but I am not so sure I would categorize discus as having a weak immune system, but rather living in an environment that without proper care subjects them to higher than normal pathogen levels.

I can't quote the source of my assertion that discus have a weak immune system, but I do remember the reasoning behind it. According to what I read, the environment that discus come from originally has a low PH. Most pathogens do not do well in low PH water, and since discus have evolved over thousands of years in this environment, their DNA did not develop a strong immune system. Please understand that I don't know this as a fact, and I am by no means an expert in this area, so you may well be the one that is correct.

Can you explain why young discus are more sensitive to unhealthy water conditions? Is it because the adult's immune system has had time to adapt to their environment?

Also, why is it that mixing discus from two different breeders can result in health problems for either or both of them? Isn't that because the immune system of either of them cannot handle the pathogens presented by the other? Could this be explained by the possibility of a week immune system?

Would be interested in your opinion on this.

[discuspaul]

I can't quote the source of my assertion that discus have a weak immune system, but I do remember the reasoning behind it. According to what I read, the environment that discus come from originally has a low PH. Most pathogens do not do well in low PH water, and since discus have evolved over thousands of years in this environment, their DNA did not develop a strong immune system. Please understand that I don't know this as a fact, and I am by no means an expert in this area, so you may well be the one that is correct.

Can you explain why young discus are more sensitive to unhealthy water conditions? Is it because the adult's immune system has had time to adapt to their environment?

Also, why is it that mixing discus from two different breeders can result in health problems for either or both of them? Isn't that because the immune system of either of them cannot handle the pathogens presented by the other? Could this be explained by the possibility of a week immune system?

Would be interested in your opinion on this.

A simple answer to your first question is yes, a young discus' immune system is still largely under-developed, hence not able to deal with health threats as effectively as more mature fish.

Again, yes to your second question, the simple answer is primarily that the stock from different breeders could well have been raised under significantly different conditions from each other. The fish from one breeder may have had exposure to pathogens that their immune systems have effectively dealt with - however they may still carry vestiges of the problem within their bodies, but have developed immunity to it. Exposing fish from another completely separate stock who have had no exposure to that particular pathogen can pick it up from the former group, and be unable to deal with it effectively - &/or vice versa.

[RogueDiscus]

This could be a sticky! I'm sure this is a question asked by many folks who are fairly new to keeping discus, but who have been successful keeping other fish. The tone is great. Keep it up!

[Jnotjane]

This could be a sticky! I'm sure this is a question asked by many folks who are fairly new to keeping discus, but who have been successful keeping other fish. The tone is great. Keep it up!

As someone getting ready to start their first discus tank, I completely agree. This information is invaluable to someone new to fishkeeping, and discus in particular. I've kept fish for 20 years, and I learned a few things from this post I never thought about before. Very insight information in this thread from some very experienced discus keepers.

[jimstreet]

I'm just a newbie to Discus but here's my simplistic view. You need to have a basic understanding of your water chemistry out of your tap and then inside your tank. This will give you a baseline to work with. Once you understand that baseline you can understand what is going on in your tank. I have recently added a timer for the light and auto-feeder. This increased the light and increased the available food. You guessed it, more algae and more poop = dirtier water. My tank is now out of balance and I am changing 20% daily to get it back to the baseline. Once I am back at the baseline I can get away with 20% changes twice a week. I am not saying don't test or change the water regularly but if you don't change anything, fish load, feeding, light etc, your eco-system is pretty constant therefore you don't need to be so rigid with water changes.

[YSS]

I'm just a newbie to Discus but here's my simplistic view. You need to have a basic understanding of your water chemistry out of your tap and then inside your tank. This will give you a baseline to work with. Once you understand that baseline you can understand what is going on in your tank. I have recently added a timer for the light and auto-feeder. This increased the light and increased the available food. You guessed it, more algae and more poop = dirtier water. My tank is now out of balance and I am changing 20% daily to get it back to the baseline. Once I am back at the baseline I can get away with 20% changes twice a week. I am not saying don't test or change the water regularly but if you don't change anything, fish load, feeding, light etc, your eco-system is pretty constant therefore you don't need to be so rigid with water changes.

What do you mean by "baseline"?

[Cabe]

World famous discus keeper Jack Wattley did an experiment years ago where he took 2 groups of discus fish from the same group and put them in 2 separate tanks. He changed the water more often in one tank than the other and after a month the tank with frequent water changes were twice the size of the ones in the other tank. He actually thought discus produce a substance that slows the growth rate of fish around them.

[DISCUS STU]

World famous discus keeper Jack Wattley did an experiment years ago where he took 2 groups of discus fish from the same group and put them in 2 separate tanks. He changed the water more often in one tank than the other and after a month the tank with frequent water changes were twice the size of the oones on the other tank. He actually thought discus produce a substance that slows the growth rate of fish around them.

That was a very good experiment at the time though we would probably understand today that the lower growth rates were probably due mostly to more adverse water conditions in the tank that had fewer water changes.

I don't know if there's anything to support the claim that was made widely 20+ years ago that adult Discus exude a growth inhibiting hormone that would effect and reduce the growth of younger still growing fish. Biologically in nature; Discus in the wild, it doesn't seem to make much sense either but this was an assertion that was made in the beginning of the hobby and repeated frequently. The older books and magazines I have from the 80's and 90's often stated this. ...So much for everything in print being valid. We know much more today and have much better information.

[Cabe]

I think in his experiment, he changed water in both tanks daily, however the tank with the fast growing fish got changed like 9 times a day.

I'm not really sure about the growth inhibiting either and tend to agree with you, but I think you could probably duplicate that water changing experiment today and get similar results.

[kris2341]

a lot of the SD old timers say that the what Jack said was totally misinterpreted and that he simply meant that dirty water was what inhibited growth when they asked him directly.

so naturally, with a tank that gets a huge number of water changes daily, they would grow better.

[John_Nicholson]

Yes of everything that Jack did I think he hates to hear about the BS growth inhibiting hormone stuff the most....LOL. Its all about dirty water. Do you think that if I shot the next ******* that mentioned the growth inhibiting hormones then this myth would finally die?

-john

[nc0gnet0]

Yes of everything that Jack did I think he hates to hear about the BS growth inhibiting hormone stuff the most....LOL. Its all about dirty water. Do you think that if I shot the next ******* that mentioned the growth inhibiting hormones then this myth would finally die?

-john

Maybe if we start calling it growth inhibiting fish poop we can kill it off over time.........

[Cabe]

http://www.discusnews.com/worldshows/duisburg2000/html/chat-jack-tue.shtml

[John_Nicholson]

Yes sunshine we have all seen that 1000 times. Me I simple asked Jack about it but if you want to keep searching the internet then please do so. It is kind of like getting caught leaving the bar with an ugly women.....yea you did it but now you wish your friends would just let it die......... Everyone says something at some point in their lives that they wish would just go away.

-john

[Cabe]

I don't believe the theory, but I think Jack did.

[dragon1974]

LMAO @ leaving with the ugly woman...

[nc0gnet0]

Are we taking into account the out of town formula?

[Second Hand Pat]

Hey, leave us ugly women out of this :p

[jimstreet]

What do you mean by "baseline"?

Baseline as in various tests I have performed along that way gives me data about how my water behaves in and out of the tank. For example, out of the tap my water is pH neutral and very soft. After 2-3 days in the tank the pH is below 6 and even softer. This data along with a visual of how much poop etc is in the tank gives me an very good indication of the quality of the water. Any change to the amount of light/food/fish/filtration changes the baseline and you need to determine a new baseline.

Does that make sense?

[CammieTime]

This is an interesting thread.

[Clawhammer]

I believe that different pathogens and organic compounds thrive in different kinds of water and environments. Over the millennia, discus have evolved in low pH Amazon water, Discus have built an immunity to low pH pathogens, but not pathogens common in aquariums. In this environment they were not subjected to high DOC levels due to low pH and incomprehensible amount of fresh water, so they have not evolved the ability to tolerate those conditions.

Also, they have not been selectively bred by people long enough to breed out these traits. Breeders select mostly for appearance, not to make them more tolerant to poor water conditions, although the forces of natural selection due exist in a tank to some extent (those who thrive better in aquarium environments are more likely to breed).

[DISCUS STU]

Breeders select mostly for appearance, not to make them more tolerant to poor water conditions, although the forces of natural selection due exist in a tank to some extent (those who thrive better in aquarium environments are more likely to breed).

I agree with this last part and believe that the domestic strains are slightly more disease resistant than wild Discus though not by much and there are hardier domestic strains than others, i.e., PB's and Red Turquoise, etc.

[Lido]

I was talking with a fisheries biologist about some of the theories on why certain fish require such pristine water condition. He said some fisheries scientist believe it has a lot to do with the shape of their body. Because they are round and have such a small organ cavity they have relatively small livers to their body size. This is why most fish are elongated (amongst other reasons of hydrodynamics). Because these fish have a very small liver relative to body, and their water condition never required them to evolve past it, they can not filter toxin as well as other fishes. Basically it is a pure result of their evolutionary track, conditioned to the environment in which they best thrived in the wild. So why do you have to do water changes with discus because Darwin and or god said so.

This is in addition to the other reasons listed. Just offering a lil more "maybe this" for ya.

[CammieTime]

Breeders select mostly for appearance, not to make them more tolerant to poor water conditions.

Has anyone ever tried to breed a really hardy discus strain that can take bad water conditions? It's like in dogs, some breeds are bred for their intelligence and companionship, regardless of their physical appearance.

[Willie]

Would you breed a dog variety that can be neglected as puppies? :eek:

[John_Nicholson]

Just because some other types of fish can tolerate crappy water it does not mean they do well in it. Take some small mollies an treat them like discus....when they end up being 6 inches long as compared to the "normal" 3 inches you will understand what I mean.

-john

[Pices]

Another maybe this reason lol106031

[Lido]

Only if they were good with neglected children. Just KIDDING don't ban me

[Mattgoanna]

Water changes are often talked about in terms of size and growth rate.
Do we know the average size of wild discus and their growth rate?
While I acknowledge that massive water changes and high protein foods results in massive fish, are we replicating what happens in the wild or what we desire in our captive fish?
Is large size a criteria for a healthy fish.......... or is a medium sized, healthy and lean breeding fish actually a good result. Every very large wild fish I have purchased is clearly long in the tooth and often the captive ones look overweight to me.

[John_Nicholson]

Water changes are often talked about in terms of size and growth rate.
Do we know the average size of wild discus and their growth rate?
While I acknowledge that massive water changes and high protein foods results in massive fish, are we replicating what happens in the wild or what we desire in our captive fish?
Is large size a criteria for a healthy fish.......... or is a medium sized, healthy and lean breeding fish actually a good result. Every very large wild fish I have purchased is clearly long in the tooth and often the captive ones look overweight to me.

No, none of us who put fish in tiny glass boxes are coming anywhere close to duplicating the environment of the Amazon. If you want to get a 10,000+ gallon tank where 100,000 gallons of fresh water flows through it daily and put 6 discus in it then we can talk about trying to duplicate the environment. I think most people vastly underestimate the amount of water in the Amazon.

-john

[DISCUS STU]

No, none of us who put fish in tiny glass boxes are coming anywhere close to duplicating the environment of the Amazon. If you want to get a 10,000+ gallon tank where 100,000 gallons of fresh water flows through it daily and put 6 discus in it then we can talk about trying to duplicate the environment. I think most people vastly underestimate the amount of water in the Amazon.

-john

+1 and right on.