# Are CO2 and ferts bad for fish health long term?



## Nont (22 Dec 2021)

I myself have never killed fishes with CO2 and have tetra breed several time in high-tech iwagumi and still manages to get a warning about fish cruelty on other website.
Are CO2 and regular ferts dosage really bad for fishes health?


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## Zeus. (22 Dec 2021)

IMO - Yes/No

Our fishes produce CO2 and ferts as natural waste products, which are taken up in the environment they are in and plants use them, so there is nothing new.
Once there was no Oxygen in our atmosphere and it wasn't until plants started photosynthesising and their waste product put Oxygen in the atmosphere which enabled higher forms of life to develop.
As long as regular water changes (WC) are done the maths shows there is no excessive built up of ferts in the water column and the effects of higher CO2 levels can be seen directly in a fishes behaviour.
So *no* if you look after your tank and don't aim for [CO2] above 30ppm  
So *Yes* if your Maintenance/WC are poor and/or use excessively high CO2 levels  

I think more fishes have died with poor maintenance/care in shipping and fish keepers then have died though high fert/CO2 levels in our planted tanks.
Plus our planted tanks IMO are a better environment for fishes than plant free tanks or heavily stocked tanks


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## CJM70 (23 Dec 2021)

Zeus. said:


> I think more fishes have died with poor maintenance/care in shipping and fish keepers then have died though high fert/CO2 levels in our planted tanks.  Plus our planted tanks IMO are a better environment for fishes than plant free tanks or heavily stocked tanks.


I totally agree.  And even more at certain “chain-style” pet stores (although they seem to be improving). My intention is not to start a site thread on fish husbandry in chain style pet stores though, so please let’s not start that debate.

I just felt it pertinent to this question.

CO2, like anything, especially in an enclosed space such as a Fishtank, is a fine balance. The more effort and interest you put into getting that balance correct, the better the fishes welfare will be. By asking this question you have already indicated that you are willing to put the effort in and you’re doing the right thing by doing plenty of research. It is also fair to say that on this forum, the membership tends to be made up of those with extensive knowledge and those who want to gain it, whereas some websites and social media pages tend to focus more on just the fish. So in asking your question here you have come to the right place 👍.  

PS I am not blowing my own trumpet with that last remark, I am still one of those looking to gain such knowledge, but I have definitely recognise the fact that there are some pretty clever people on here.


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## PARAGUAY (23 Dec 2021)

You cant seperate the other thing CO2  fertisation and healthy plants. So in a balanced planted tank  CO2 and fertilsers lead to healthy long lived(IMO) fish. Same really in a tank with no added CO2 .Healthy plants is the aim. More needs to be considered with pressurised CO2 because anything going wrong can kill livestock. So really as above post @CJM70 its down to the individual aquarist to put the time and effort wih CO2


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## Nont (23 Dec 2021)

Thanks for your opinion, everyone. I can see that people here are more open minded.

I used to get bashed by peoples on other forum for using ferts and high-tech stuff in general. I even got bullied for having lots of kuhli loaches in 5 gals tank instead of teaching about stocking. That really made me fear of posting anything in the forum.


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## tam (23 Dec 2021)

I think the answer is a sorts of yes, but also there are a lot of things bad for fishes health and a lot of things that we don't actually have data to determine either way. If you have two otherwise identical tanks and one has CO2 pumped in, the odds of something happening that effects the fish are higher as you've added another point for potential failure - it could also be the tipping point in other situations (a heater breaks and fish are less able to cope with rising temps etc.). On the other hand though, tanks with CO2 added are also likely to correspond with tanks that receive more regular/higher water changes so water quality can be better - so if you averaged it out you what you lose for one you might balance out the other.


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## jaypeecee (23 Dec 2021)

Hi @Natthanon 

Regarding the CO2 side of things, please take a look at the following, which deals with nephrocalcinosis in ornamental fish:



			http://www.bioflux.com.ro/docs/2016.574-579.pdf
		


It's worth a read.

JPC


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## jaypeecee (23 Dec 2021)

Hi again, @Natthanon 

You may also want to take a look at the following UKAPS thread:






						Does CO2 injection cause disease? Thoughts?
					

Hi All,   Just read a blog from Nathan Hill. What are your thoughts / take on this?   http://www.practicalfishkeeping.co.uk/content.php?sid=6769



					www.ukaps.org
				




JPC


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## MichaelJ (23 Dec 2021)

Hi @jaypeecee    Any studies about CO2 concentration in our fishes natural habitats? ...  I only find truly depressing studies and stories about how the Amazon is now emitting more CO2 than it consumes... kind of breaks my Christmas spirit 

It seems to me that injecting CO2 is perfectly safe if your mindful of the extra demands it puts on you with regards to maintenance, quality equipment etc. and stay fairly well below the conservative CO2 ppm limits.  I bet far more fish in relative terms dies prematurely due to general neglect, poor maintenance etc. than specifically due to CO2 poisoning, but I don't know the stats.  Even among all the "beginner CO2" posts here on UKAPS it's been a long time since I saw anyone killing their fish due to CO2 poisoning.

Cheers,
Michael


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## Tim Harrison (23 Dec 2021)

It's not always the case, but I tend to believe a successful planted tank and good animal husbandry go hand in hand. Learning and caring about growing aquatic plants and therefore natures flows and cycles perhaps equips an aquarist with the knowledge and awareness needed to keep aquatic critters happy as well.

And a heavily planted and well balanced CO2 injected tank should be saturated with O2. The two gasses are not mutually exclusive. All to the benefit of both plants and critters. So in answer to the OP there is no reason outside of ignorance, laziness, or wanton neglect why CO2 and fertz should be detrimental to fish health long-term.


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## jaypeecee (23 Dec 2021)

Tim Harrison said:


> And a heavily planted and well balanced CO2 injected tank should be saturated with O2. The two gasses are not mutually exclusive.


Hi @Tim Harrison 

In my view, you have made very important points here - particularly, the second sentence. And, this is something to which I have given a lot of thought just recently. No Eureka moments, just a lot of thought! 

JPC


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## MichaelJ (23 Dec 2021)

jaypeecee said:


> Tim Harrison said:
> 
> 
> > And a heavily planted and well balanced CO2 injected tank should be saturated with O2


Hi @jaypeecee,  Regardless of CO2 injection... I mean, in the night (outside the photoperiod) plants and fish compete for O2, so you got to make sure you have as much O2 as possible at any given time. Less of an issue during the day obviously where the plants "exhale" O2, but still. 

Cheers,
Michael


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## jaypeecee (23 Dec 2021)

MichaelJ said:


> It seems to me that injecting CO2 is perfectly safe if your mindful of the extra demands it puts on you with regards to maintenance, quality equipment etc. and stay fairly well below the conservative CO2 ppm limits.


Hi @MichaelJ 

First things first - I am a CO2 user in some of my tanks. But, when it comes to "conservative CO2 ppm limits", I'm not sure how they were determined. The CO2 upper limit that I have been weaned on is 30 ppm. But, I choose not to exceed 20 ppm.

For some time, I have had difficulty accepting the rationale behind the suggested 1 pH drop when first setting up injected CO2. If you're interested:






						Why Advise A 1pH Drop?
					

Hi Folks,  I don't understand why a 1pH drop is advised when setting up a profile for injected CO2. For example, if the water KH is 4dH and the starting pH is 7.3, the CO2 concentration will be approximately 6 ppm. But, after a 1pH drop to 6.3, the CO2 concentration will be a staggering 60 ppm...



					www.ukaps.org
				




JPC


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