Worried - Is CO2 Killing My Fish

[LindaC]

I have been loosing my fish over the past month, ever since the pressure gauge on my Milwaukee all in one regulator blew out, yes this could just be a coincidence but after loosing my last Otto last night, I am very concerned that this might be the problem.

It blew out right before I went on vacation and right before I left my female apisto red tail died on me. Then while I was on vacation, my female Blue Ram died. Once I got back, I noticed that my male Ram wasn't looking to well and acting strangely, loosing weight and then he died. Last week I picked up 4 Neon Tetras at the LFS and they all died and took my two Lemon Tetras along with them. My Lemon Tetras were very hardy, I've had them for almost a year, they lived through my tank cycle, two ICK outbreaks and were swimming around with such vigor only a couple of days before they died.

I thought the Tetras died because of the Neons bringing in some bacteria and me not putting them into QT before I added them to my tank, but then a few days later I found one of my two Ottos dead and just this morning found the other one dead.

The last remaining fish in my 29 gallon planted tank is the male Apisto red tail, who appears to be okay but has been doing this funny thing with his mouth lately, like he's chewing gum and this morning before I left for work, I turned on the light and he wasn't doing it, which leads me to believe that these deaths have something to do with the CO2.

My water parameters are all fine, 0 ammonia, 0 nitrites, nitrates 15-20, KH is 70 ppms and PH is between 6.5 -6.6. I have a couple of different test kits, the Hagen and I also have a PH reader in my tank, the new ones by Mardel that last for 4 weeks.

Would the pressure gauge have something to do with this? If it wasn't for the red tail breathing strangely at night, I wouldn't be concerned about the CO2 but this leads me to belive he's having a hard time breathing by the end of the day. I finally ordered a new CO2 regulator, it's been shipping and I should receive it on Friday. I bought the Best of the Best this time for aquariumplants.com.

Any thoughts or advice is greatly appreciated. I'd hate to loose my red tail, he's a big boy and been with me for 9 months.

Thank you!

 

[Purrbox]

Based on your readings you only have 29-37ppm of CO2 in your tank. If you test results are accurate, then you are well within safe bounds on your CO2 levels.

Since you're seeing lots of deaths all of the sudden, perhaps there's something going on with with your water supply? Could something have been inadvertantly introduced to the tank like soap from your hands? Anything else new added to your tank within a couple of months before the deaths started occuring? A better description of the sick fish behavior would help too.

 

[malkore]

CO2 isn't the problem. your levels seem fine. if fish are gasping, they are low on oxygen. CO2 doesn't displace oxygen as it builds up...the two exist harmoniously.

GBR's have always been very touchy for me...I used to lose one after ever water change when I tried to keep them...all my other fish are fine.

 

[gfink]

CO2 isn't the problem. your levels seem fine. if fish are gasping, they are low on oxygen. CO2 doesn't displace oxygen as it builds up...the two exist harmoniously.

GBR's have always been very touchy for me...I used to lose one after ever water change when I tried to keep them...all my other fish are fine.

I second this opinion:

You need to minimize surface agitation to keep CO2 in, but if you do too good of a job there won't be enough O2. Yes, if you have a healthy growing tank, the plants will make O2 during the day, but not at night. Many people turn on an airstone at night.

I seem to have enough surface agitation to keep O2 levels good all night. (but I did kill 4 or 5 fish when I first tried to minimize surface agitation)

 

[LindaC]

Well I'm glad it's not the CO2 but have not idea what it could be, I haven't added anything different to my tank in the past few months. This is what has me so upset. The other thing is, they're not showing any signs of sickness before they die and none of them have gasped at the top for air. My Lemon Tetras were chasing each other back and forth like they always have during the day and then that evening, I turned off the lights and within 30 minutes, one tetras was gone and then a few hours later, the other was gone. I did notice the second tetra sort of just staying in one place shaking a tiny bit but they've done that before. The ottos also were fine and then gone.

The Rams I can understand, I know they're very sensitive and I've lost a few in the past, especially females, however my male as been with me for months, so that was a surprise. The Lemon Tetras I can contribute to the Neons maybe infecting the tank somehow. I cannot put a finger on why the male apisto looks like he's chewing gum late in the day and early evening and then looks fine in the morning, other than he's having a hard time breathing.

I did put an airstone in the tank this morning before I left for work, in case some how there's just not enough O2 getting into the water. I'm just so baffeled. I have new fish coming, Kribs and some more Apisto Orange Flash, I sure hope that they'll be okay. I just did a 50% water change yesterday, so I'm hoping if there was anything foreign in the water, it's gone.

 

[Zezmo]

FWIW, if you kill fish by excess CO2, it is usually because of an extreme Ph drop caused by extreme CO2. If you are testing Ph and it is normal range, then this is not your issue. Acidosis (sp?) tends to make fish swim upside down and jump out of the water and such.

Now, low O2 is also very stressful on fish. Weak fish may get sick, old fish may just die. Low O2 and excess CO2 are generally separate issues.

 

[LindaC]

Okay, thank you very much Zezmo, this makes me feel a little better.

 

[sherry]

actually zez, ph drops from co2, as opposed to from dissolved solids are less and less considered a factor to fish one way or another after reading a bit about this from folks on aquatic plant central and from tom barr, i stopped buffering my kh1 tank altogether. ph is routinely around 5.7 and the fish are doing fine.

 

[Purrbox]

FWIW, if you kill fish by excess CO2, it is usually because of an extreme Ph drop caused by extreme CO2. If you are testing Ph and it is normal range, then this is not your issue.

Actually the PH drop isn't going to affect the fish. It's been repeatedly shown that PH shifts caused by CO2 are harmless to fish. A shift in pH will only harm the fish if it is accompanied by a shift in KH. It's really the KH change that hurts them and not the pH, however more people test for pH and this is why it gets associated with the problem instead of KH.

High levels of CO2 on the other hand can hurt fish. Basically the high levels of CO2 prevent their gills from being able to expel the CO2 in their systems causing them to sufficate. For this to happen you have to have extremely high levels of CO2, 100ppm or higher.

 

[Wizzard~Of~Ozz]

I have my water the same as yours, KH 4deg PH 6.5-6.6 Co2 on average is 37ppm. No mysterious deaths.

My male GBR died, (tho I haven't found the body, he wasn't eating, the 2 females are doing great tho).

FWIW tho. Co2 can only cause deaths by suffocation if it's allowed to rest on the surface (tight fitting glasstops for example) which doesn't really displace oxygen, but rather doesn't allow O2 to reach the surface of the water. Purrbox also mentioned acidosis which causes a ph crash in the fishes blood (they can't dispell the Co2)

With the current season at hand, I have to ask what the temp of your water is.

If I had to guess as to what the culprit is, I would say a change in your water supply. There was a reason for fish "yawning" but I can;t remember what it was. I think I came across the information while researching Bala sharks.

Oh, and purrbox is right about the ph swings from Co2. it seems fish are more concerned about rapid changes in hardness more then the PH of the water when it's induced by Co2 Injection. (said GBR's were dropped from a bag with PH 7.3 into PH 6.5 with no shock at all). Also when I got my tank setup, I dropped the PH from 7.8 to 6.8 in less then 1 hour. no ill effects.

 

[LindaC]

The temperature of my water is pretty much always the same at 26 C. it might flucuate a degree or two once in a while but I wouldn't think that could hurt them, or could it?

I was reading somewhere that Lemon Tetras can perish if PH drops lower than 6.8, I wasn't aware of this and I wonder if that's the reason. You know what, I may never know the reason for all these deaths, if it were a couple of fish then I could say that their time was up but there were just too many within a short period of time. I only hope that going foward, this does not happen again, it's been a very trying month for me and my fish.

I really appreciate everyone's help, thanks again!

 

[Zezmo]

I hear what you are saying, and under normal type conditions I agree, Ph shift due to CO2 has less affect on the fish. But, I can tell you with certainty, that in the past I have had my low Kh tank get to extreme CO2 (over 130ppm). This killed all shrimp, and weak fish. And many of the healthy ones were suffering from acidosis. I stopped the problem, not by a water change, but by disconnecting the CO2 and running an airstone.
I am quite aware of what you are saying, and generally agree (Ph swing via CO2 not a big deal, and Kh swing being a big deal). The question was one about "is CO2 killing my fish". My comments are based on personal experience in exactly how you can use CO2 to kill your fish. And that is done by turning your tank into a vat of carbonic acid.

Basically the high levels of CO2 prevent their gills from being able to expel the CO2 in their systems causing them to sufficate.

This implies you have reached the point where Co2 is at saturation (not sure how many PPM's that would be). Now, I am not saying that is not possible. I don't know. I do know, that if a fish of mine does not get properly drip acclimated to my very low Ph tanks, it will react by doing piroets and swiming upside down, and if not rescued will usually die in short order. The fish already in the tank will be fine, just the un acclimated one will suffer (these are lessons learned the hard way ). I mention these symptoms, as the same symptoms I have seen when CO2 hits an extreme level. So, is it exess acidity of the fishes blood (acidosis), due to no being able to expel the CO2, or is it due to being in acidy water.
I don't claim to be able to answer that specifically.
Certainly raises some questions: Does the CO2 in a fishes blood normalize to the CO2 content of the water? if not, What then limits a fishes ability to respirate CO2? Due to osmosis (which in freshwater, is water constantly osmosing into the fishes body), is a fishes internal Ph affected (adjusted) by the water's Ph?

Bottom line, I was trying to indicate via my anecdote that it is very unlikely that Linda was killing her fish with CO2. That it in fact takes some "extreme" conditions to successfully use CO2 to wipe out your fish.

 

[Wizzard~Of~Ozz]

Zezmo,

It's not about fish being unable to expel Co2, it's about reducing the efficiency of that. The more Co2 the water has in it, the less it can absord. the same is true for O2 (hence pearling at satuaration). If @ 40ppm the fish can consistantly have 80-90% of the Co2 expelled then it will be fine, however @ 140ppm that mechanism goes down and they can only expel 10%, well for that to work they would need to breath 10x faster to displace the Co2.. So yes, Co2 can kill fish, but not at 37ppm, nor can the ph swing associated with it. Chances are the answer lies elsewhere.

1-2C swing is about the same as fluctuating from 76 - 80f daily. That can certainly affect the fishes stress level. but doubtful it would cause them to die. I think water contaminents is still the most likely for such sudden deaths.

 

[Plantbrain]

100ppm or more, you can count on CO2 death, but it's not the pH that causes the death.

Generally folks havign issues when they try to achieve decent CO2 ppm s often have no surface movement, not enough, I like a nice ripple going in all my tanks.

It waste a little CO2, so what? It's easy to add and cheap.

the O2 and the CO2 both do not get depleted or build up(CO2), so both are more stable and the fish are fine with higher levels of CO2.

Good mixing is essential for CO2 enriched systems to run well and this becomes more of an issue on larger tanks.

Most that think Discus don't like CO2 at 25-30ppm etc don't have enough O2, it's not the CO2 .........but that can cuase an indirect effect and weaken some weak fish if the O2 is also low.

But the real issue is the O2.

Move that water!!!
You'll also see better plant growth and generally not much CO2 losses.

I think it's rather peculiar that folks whine about high CO2 and excess ferts effects on fish, but then they add CO2 24/7.

There's no need to add it other than during the day, plants don't use it at night, it's not good for the fish really, and the O2 is also higher during the day when the CO2 is being added.

So you can save some CO2, a lot, right there.

FYI, what happens every day in a lake full of plants to the pH?
It goes anywhere from 2 to 4 pH units.
Everyday.

Fish seem fine in nature...............

Not sure why pH issues are brought up, I do 50-80% water changes to wimply SA fish each week with tap. the change is about 1.0 units in 30 minutes, enever lost a fish yet, the fish sure like it based on behavior and feeding.

So it's not the pH that's the issue clearly..........this is true for the natural systems and our tanks with CO2.


Regards,
Tom Barr

 

[LindaC]

I have an airstone running in my tank every night now since the last fish death and my CO2 system is on a timer and shuts off every night with the lights, so it's not running 24/7.

I was under the impression that movement in the tank caused CO2 to dissipate into the air and not into the water column. Maybe I should get a powerhead for the other side of the tank, I'm not a big airstone fan, I think they're an eye sore but if they help the fish, I'm all for it.

When the CO2 comes back on in the morning, after being off all night, will the fact that it takes the PH a while to down to it's ideal level be a factor for fish? My PH is at 7.0 - 7.2 in the early am before the lights go on, and then it drops down to 6.6-6.5, isn't that a rather drastic drop every day?

 

[Zezmo]

I have certainly learned something from this discussion. That is why I like coming here

 

[Purrbox]

I think that what PlantBrain is trying to say that it's not necessary to keep the surface of your tank rock still. A slight ripple will loose a minimal amount of CO2 but will also promote good O2 exchange. The power head would probably be an excellant idea as it will improve water flow, and allows you to decide the exact amount that you're willing to have the surface disturbed by adjusting the out put direction.

PH swings due to CO2 do not hurt fish. It's only the pH swings due to changes in KH that hurt fish. In reality this probably means that changes in pH don't actually hurt the fish just changes in KH, but because more people test for pH it's what gets associated with the problems.

 

[LindaC]

I know I've gathered a wealth of information since I've been visiting this site and learn something new almost every day.

I now understand and agree that CO2 will not hurt my fish or the swing in the PH due to injecting CO2. My KH stays the same and I do test it now and then to make sure and every time I do, it's at 7.0. I buffering my water by adding 1/2 tsp of baking soda with every 50% water change.

I now think that I introduced some type of bacteria to the tank, either that or the batch of Neons that I added might have been sick and infected my other fish.

On a good note, my male Apisto is doing fine, I moved the pair of Rams I had in my 10 gallon tank (currently blacking out due to BGA) over to the 29 gallon and he's busy chasing them around, so hopefully whatever it was is gone now.

 

[Lonewolfblue]

With my CO2 running, I also like some surface aggitation, running a small airstone in the tank. With what minimal CO2 loss you have, you will find that you will maintain about the same CO2 levels with a pressurized system even with the bubbler going. And this will ensure the fish will have adaquate O2 levels.

 

[Plantbrain]

If you have too much CO2, the faster off gassing will also help.
And when you turn the CO2 off, the excess degassess rapidly.

Regards,
Tom Barr