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What’s the point of changing water for discus?


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I’ve been keeping discus for the past year, I absolutely love them. I have a breeding pair, I’ve been growing out their fry, and I have 10 medium sized ones in my display tank. They’re one of my favorite fish. 
 

I’ve always been super diligent about water changes but that’s because the internet has told me to be. But why? I understand changing the water daily in the fry grow out tank and the breeding tank due to how heavy I feed and how small of water volume they have.
 

But why change water in my display tank if the plants are sucking the nitrates from 20 ppm to 0 in about 4 days? Is there any reason to actually change their water if the plants are scrubbing it clean for me or is there more to it than that for discus? 

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I haven't kept them myself but I know some forum members like @Daniel have kept them for years. From how I understand it, discus are especially sensitive to nitrates and grow larger and stay healthier in a 0-nitrate environment. Since the temperatures they like are very high, higher than most plants enjoy, they're often raised in bare-bottom tanks with only hardscape, so all nitrates have to be removed manually.

I personally think, as long as you stay regular with it and are getting plants to grow in your discus water, a weekly water change should suffice. But a more experienced discus keeper might have more info.

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Posted (edited)
24 minutes ago, PumpkinWeevil said:

I’ve been keeping discus for the past year, I absolutely love them. I have a breeding pair, I’ve been growing out their fry, and I have 10 medium sized ones in my display tank. They’re one of my favorite fish. 
 

I’ve always been super diligent about water changes but that’s because the internet has told me to be. But why? I understand changing the water daily in the fry grow out tank and the breeding tank due to how heavy I feed and how small of water volume they have.
 

But why change water in my display tank if the plants are sucking the nitrates from 20 ppm to 0 in about 4 days? Is there any reason to actually change their water if the plants are scrubbing it clean for me or is there more to it than that for discus? 

I think you raise a fair question. I think there’s something to discus being more sensitive to “poor water quality” on account of their slime coat, which is more susceptible to infection than other fish.

But this just begs the question you are already asking: how is water quality “poor” when plants are filtering out nitrates? I think that water “quality” is more complex than the nitrogen cycle. TDS build up over time in ways that _may_ be stressful on discus. Water changes help to cut that out.

But, having said that, maybe check on some of the more extreme ends of the spectrum. Message Jack Wattley Discus, and ask Gabe for his insights. Reach out to Lucas R Brett, and ask about his _no water change_ philosophy and how well his discus do. Contact Ocean Aquarium store, San Fran, and ask if they do Discus in their “no water change” tanks. 

Edited by Fish Folk
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The good thing about frequently water changes in a discus aquarium is that many people have tried it over a long time period and found that it works. But that doesn't mean that it is necessary.

I don't know what discus are sensitive to, but it could be nitrates as @Kirsten mentions above. What they seem to want is water that has very little of anything in it, that is clean water. One the easiest way to get clean water is do a lot of water changes. When I have discus in smaller aquariums I change the water regularly and the discus seem to appreciate it.

But when I have discus in larger aquariums I don't change the water very frequently. When you have a large volume of water, feeding and the wastes that feeding produces just doesn't have the impact that it does in a smaller aquarium.

 

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1 hour ago, Daniel said:

The good thing about frequently water changes in a discus aquarium is that many people have tried it over a long time period and found that it works. But that doesn't mean that it is necessary.

I don't know what discus are sensitive to, but it could be nitrates as @Kirsten mentions above. What they seem to want is water that has very little of anything in it, that is clean water. One the easiest way to get clean water is do a lot of water changes. When I have discus in smaller aquariums I change the water regularly and the discus seem to appreciate it.

But when I have discus in larger aquariums I don't change the water very frequently. When you have a large volume of water, feeding and the wastes that feeding produces just doesn't have the impact that it does in a smaller aquarium.

 

I have 8.2 ph liquid rock water (the discus were bred and raised in local tap water so they’re healthy and happy) so I’d argue it’d be better for me to not change water so the TDS and ph lower over time. As far as nitrates go I’m having to add a few pumps of easy green daily just to keep it from hitting 0 ppm in my 120 gallon display

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Just now, Daniel said:

More than 125, maybe 225...for me it is the 500 gallon tank in livingroom. My next largest tanks are 75 gallon aquariums, big enough by normal standards, but not that large when it comes to discus.

Thanks! That’s exactly what I wanted to know. I saw your first comment and immediately started thinking I could have an easy 75 gallon discus tank. I’ll guess I’ll have to dial back my expectations a bit. 😀

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3 hours ago, Daniel said:

@PumpkinWeevil you could right. Clean water is a slippery concept. If you are having success, I would mainly keep doing what you are doing, but throw in a couple of experiments to spice it up and keep it interesting.

I’ll start pushing the water change a couple days and watch the fish. 
 

I don’t mind changing water, I actually really enjoy it. I just don’t want to waste resources if I don’t have to. 
 

thank you for your input 🙂 

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On 5/4/2021 at 12:56 PM, Fish Folk said:

I think you raise a fair question. I think there’s something to discus being more sensitive to “poor water quality” on account of their slime coat, which is more susceptible to infection than other fish.

But this just begs the question you are already asking: how is water quality “poor” when plants are filtering out nitrates? I think that water “quality” is more complex than the nitrogen cycle. TDS build up over time in ways that _may_ be stressful on discus. Water changes help to cut that out.

But, having said that, maybe check on some of the more extreme ends of the spectrum. Message Jack Wattley Discus, and ask Gabe for his insights. Reach out to Lucas R Brett, and ask about his _no water change_ philosophy and how well his discus do. Contact Ocean Aquarium store, San Fran, and ask if they do Discus in their “no water change” tanks. 

Great suggestion about contacting Jack Wattley, Lucas Brett, and Ocean Aquarium. I bet they all have some interesting perspectives. 

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