Question regarding water changes

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platytetrafan

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Jan 20, 2007
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Hi all it’s been a while since I’ve posted & wanted to get your opinions.Hope everyone is doing ok during this covid pandemic. A few months ago I added 2 discus to my 36 gallon corner bow. The discus were smaller than the usual size & from what I read I think they were stunted.

They ate well
swam & chased around one another & got along with my other fish. I have tetras cherry barbs rainbow danio & cories. My water parameters were fine & I was doing 50% weekly water changes which I was told is essential to do for the discus & my other fish were tolerating the routine.

Unfortunately & I don’t know why but one of the discus died about 3 months ago I think it was a female & she was smaller than the other discus. There was no obvious sign of illness on the body so I assumed it was something internal she died from. I just bought another discus to replace the one that died & it’s in QT. My question is re: amount of water am changing out of 36 gallon weekly LFS employee told me 50% weekly is too much water that I could get away with doing 25% biweekly. What do you think? I just did a 25% Wc & gravel vac today & value opinions given in this forum. If I do 25% wc’s still do them weekly or biweekly? Thanks stay safe all.
 
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fishorama

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Jun 28, 2006
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Well, when I raised "quarter sized" (seller sized, lol) discus I changed 50-75%+ water every single day until they hit 3 inches or so. Then I relaxed it a bit to a still paranoid 4 or 5 times a week. I fed 5-6 times/day, made my own seafood & beef heart mixes & fed other foods, no repeats in a day.

If they were truly stunted, as opposed to slower growing, their "insides" grow at a normal rate, but not their outer bodies to fit those insides...if that makes sense.

Even with all my seeming heroic efforts, half were smaller, maybe3.5- 4.5 inches at most; the others were 5+ inches to 6-ish. I had to move & sold them to a discus club friend & some immediately paired up & spawned with viable looking eggs. Sadly there was a long power outage & he lost them all (sniff).

So that's my sort of successful discus saga (best I've ever done)...If you really want to breed them you need to start with at LEAST 2 compatible discus in a 29g+ tank with no other fish. A 36 bow is not big enough for more than a true pair of discus...well, or maybe 2 females if you're lucky & they're compatible. Really they prefer a group of at least 6 in a much larger tank...until they pair up, if they do...2 is not ideal...wimpy as they can seem they are cichlids after all.

My best advice after all that is change lots water every other day & keep your fingers crossed. Discus are hard. People say they're not really...if you meet all their many needs. Yeah, right...
 

FJB

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Jun 7, 2019
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What fishorama said +1, many times.
I have not had discus in a while, but did have many (at the same time), for years. Mostly wilds. A photo below as example.
My WC routine involved 50-80% water changes daily. Granted, the main food back then was live food and beefheart, which is messy. But discus and skimping on water changes never works.

Symphysodon aequifasciatus Wild Large LatB.jpg
 

fishbuddha

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Aug 2, 2020
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Generally, I would recommend 25% water change weekly. Doing larger amounts could affect de-nitrifying bacteria ecosystem. You want to maintain a balanced environment over time, and try not to shock the system with drastic changes in water condition.
 

FreshyFresh

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Generally, I would recommend 25% water change weekly. Doing larger amounts could affect de-nitrifying bacteria ecosystem. You want to maintain a balanced environment over time, and try not to shock the system with drastic changes in water condition.
Absolutely false.

Simply put, if water changes effect the balance in your tank, you are not doing enough of them.
 

fishorama

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25%/week is WAY not enough IME. Even 25% every other day is a very minimum & not great at that, especially with other fish in there. If you can't commit to lots more & lots larger WCs then discus are not for you. Make the effort or get other fish. You "might" be able to reverse some of the slow growth with better husbandry but there is a point of no return to discus health.
 
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fishbuddha

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If you’re feeding them 5-6x/day, then it makes sense you would need more frequent water changes. However, that feeding schedule seems excessive in my opinion. I would make sure water temp. and pH are in the right range for discus.
 

FreshyFresh

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Please explain why this is false.
Unless it's a special breeding project you're after or you are keeping non-captive fish that require parameters that the water you use doesn't offer, your tank's water parameters should match the tap water you use. The easiest way to maintain that is with regular water changes. For a planted tank, you are replacing trace elements this way, that are being used up. You also won't have to worry about chasing pH around, which IMO is a loosing battle.

If you allow basic things like gH and KH to ramp up out of control due to regular topping up of the water level w/out doing water changes, eventually your tank's pH is going to shift drastically. Do a large water change now and it's going to pose a threat like you mentioned above.

This is just my basic understanding of how this goes. Hopefully one of our superior brain buckets will chime in. We seem to have taken on more superiors lately which is wonderful!
 

FJB

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Please explain why this is false.
Nitrifying and denitrifying bacteria are largely benthonic. That is, they live almost exclusively as biofilms on surfaces (every surface of the tank, including those parts of your filters you clean in manners that don't kill them, i.e., with de-chlorinated water). A small minority of these bacteria are in the water column.
Please realize that those beneficial bacteria are not limited to the parts of the filtration systems that people consider "biological filter".
Thus, water changes (of any size) would have minimal impact on those bacteria, unless chlorinated or otherwise toxic water is used.
 
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