# When CO2 strikes: killing all my fish



## green_valley (Sep 14, 2011)

Hello everyone,

It's been about 3 weeks now that this disastrous incident happened. I have finally "somewhat" moved on and am able to share the story. In the beginning of the month (April), I wanted to rescape my 50G tank (here is the journal: http://www.plantedtank.net/forums/tank-journals/156848-green-valley-goes-more-than-green.html). Even though the tank has been great since last year, I wanted something different. 

Before:









After:










It was fun (getting all the stuff clean up). I was pretty happy with the new look. Then I started to adjust CO2. Also I am using the splitter to distribute 50G and 10G tanks. After a few days, I realized that I needed to do more tweaking as the CO2 wasn't coming up enough. After fixing it, I woke up in the morning, and I saw the CO2 didn't turned off. However, I didn't see any issue with my fish. They were still happy and looked healthy. Well, more tweaking needed obviously. 

At this point, I am still trying to find out what's actually happened. I was basically trying to get all working together (timer, splitter, cylinder valve, regulators). Somewhere along the line, I made a huge mistake. I left the tanks for less than 3 hours, and when I got home, this is what I found:






































I was shocked, sad, angry, pissed off, etc. It was a disaster. I tried to rescue some, but they didn't survive. 

As I told you earlier, this CO2 was connected to another 10G tank. I lost all of my fish there as well. What's even more sad news, I was loosing a battle with brown algae on that tank.

Before:









After a month:









So yeah, it was painful. As far as the fish casualties from both tanks, I lost all these:

Neon Tetras (x 40)
ForkedTail Rainbow (x 4)
SAE (x 6)
Corry (x 4)
Bumble bee Gobi (x 2)
Pseudomugil gertrudae (x 4)
Rummy Nose (x6)
CPD (x 6)
Scarlet Badis (x 6)
Otto (x6)

:fish::fish:RIP :fish::fish:


So yeah, I was considering to drop out of this hobby. But guess what, if it doesn't kill you, it makes you stronger. I will comeback even better and I have learned hard way. I thought that CO2 disasters would never happen to me. Yes, it could happen to anyone. I just hope that this might be an eye opening for fellow hobbyist, since I do not want this to happen to anyone. Be careful on CO2.

LIFE GOES ON,


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## HD Blazingwolf (May 12, 2011)

Man i've been there. i thought the same thing. im too careful. it'll never happen to me

i've been gotten. lost all my fish. and one i particularly came to love as it would roll over in my hand if i set my hand in the water.

i feel your pain. if it helps i, as a grown man, cried when my fishies died.


i took about a 1 month hiatus. i let the tank go as it was. didn't change water. just added ferts occaisionally. after my month i felt better and started by tearing my tank down and starting over. i've learned much since then


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## fusiongt (Nov 7, 2011)

Just remember it's all about balance. In your last picture, it's obvious there was just too much lighting on as the plants were dense enough to make use of it + the CO2 = more algae. It happens... especially early on when the plants aren't established.

As for your large tank, just look at it as a new start. You have a large tank... going for cardinals isn't that exciting (at least not to me). Try a different breed... roseline sharks are beautiful for example. 

What's alarming is that you said your CO2 didn't turn off... but people here leave their CO2 on all the time. Less is more in this case. Less = plants alive, fish alive. More = more algae, dead fish. So it wasn't that the CO2 didn't turn off, it's more like you just put turn it on too much and they suffocated. It should never be on so much that if the plants aren't producing O2 (at night for example) that the fish die immediately. But you're almost there and you have all the equipment so I hope you have better luck next time around.

The hardest part of this hobby is patience - "PLANTS AREN'T GROWING 10 INCHES A DAY? CRANK UP THAT CO2 AND PROFIT" is the wrong mindset. Patience patience patience.


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## jeremyTR (Mar 21, 2012)

Ouch! I'd punch myself in the face if i ever did that to myself.


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## AUvet14 (Apr 11, 2011)

Yup. I killed all of my amano shrimp that way. Cranked the CO2 up too much, say my rasboras huffing and puffing at the surface, turned CO2 down, then found all the shirmp dead later. :-/ It's definitely frustrating


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## In.a.Box (Dec 8, 2011)

What kinda co2 setup was you using?

And that's ton of brown Algae my Otto will live happy with all that algae.


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## FlyingHellFish (Nov 5, 2011)

That happen to me once when my solenoid was unplug but kept pumping Co2 overnight. I had to blast out the dirt in the solenoid, it got stuck somehow. 

Never buy those cheapo asian style regulators you see on ebay for cheap, I think they pump out a couple of working units and mass produce the rest. 

I think the OP is using an Aquatek but I only hear good things about those.


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## plantbrain (Dec 15, 2003)

I nag nag nag people about CO2, instead they fuss and heehaw over ferts......I've never seen anyone kill fish with ferts, in 15 years...........

CO2? Every week a story like this.

I think many simply have to learn the hardest way. Or they give up.


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## jcgd (Feb 18, 2004)

Truth be told, I almost had this happen once but just before it was too late I discovered that I did in fact have cherry shrimp in my tank. I didn't know I had them in the tank (it was full of large rainbows) but when the co2 was too high they were the first to the surface, where I discovered them.

It looks like cherry shrimp can be somewhat early indicators.


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## mordalphus (Jun 23, 2010)

jcgd said:


> Truth be told, I almost had this happen once but just before it was too late I discovered that I did in fact have cherry shrimp in my tank. I didn't know I had them in the tank (it was full of large rainbows) but when the co2 was too high they were the first to the surface, where I discovered them.
> 
> It looks like cherry shrimp can be somewhat early indicators.



My otos bite it before the cherry shrimp. Those are my indicators.

I added a second diffuser to my 50g last night, but cut the bubble rate to both in half. Woke up this morning to a dead oto and a bunch of surface breathing roselines. Pulled my outflow up immediately and turned the bubble rate down a little bit. ugh.

Cherry shrimp were fine though, all motoring away at the bottom of the tank as usual.


I think with some fish it's hard to tell when they're having a hard time breathing, so it's important when adjusting your CO2 to be around while it's adjusting. I usually do my adjusting on the weekend if my co2 is in need of adjusting for that reason. 

Sorry about your loss.. it's tragic, but really no reason to quit the hobby!


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## HD Blazingwolf (May 12, 2011)

mordalphus said:


> My otos bite it before the cherry shrimp. Those are my indicators.
> 
> I added a second diffuser to my 50g last night, but cut the bubble rate to both in half. Woke up this morning to a dead oto and a bunch of surface breathing roselines. Pulled my outflow up immediately and turned the bubble rate down a little bit. ugh.
> 
> ...


 
in these cases i find flow to usually be the culprit, but i do use my oto's as much of my gauge. none of my fish ever surface when the are stressed. they just hide, and stop being active. and for my ottos i judge them differently. usually they are breathign rapidly. if i see them sitting in one place breathing really slow. i know its too high


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## josolanes (Feb 28, 2012)

Sorry about the losses *green_valley* 

I nearly lost mine when I was in a hurry and unknowingly increased the co2 (quite a bit actually). When I realized it was too high, the diffuser was just pouring bubbles out - I've never seen that many before. And they were (mostly) being sucked in by my XP1's intake and mixed this way so much of it did get into the water

All my mid-swimmers were at the surface gasping and my cories were sitting frozen at the bottom. Interestingly, my ghost shrimp and snails seemed unaffected. Fortunately I had no casualties as I shut the co2 off overnight and turned the lights on to help the plants soak it up - they all began pearling almost immediately when lights went on. I realized this around 1230a and had to leave for work at 630a in the morning. I didn't sleep until about 145a so I can watch and see how they were doing. The mid-level fish (platies) calmed down pretty quickly but the cories still seemed stressed so I didn't sleep until I saw all cories beginning to swim around, even a little, again

I was running an ASA on/off with needle valve setup and within a couple of days (funds permitting) I ordered a regulator from maknwar. I currently have co2 off as I don't trust the asa on/off needle valve setup any more


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## green_valley (Sep 14, 2011)

HD Blazingwolf said:


> Man i've been there. i thought the same thing. im too careful. it'll never happen to me
> 
> i've been gotten. lost all my fish. and one i particularly came to love as it would roll over in my hand if i set my hand in the water.
> 
> ...


Thanks Blazing for sharing your story too. It's tough mannn, specially if you somewhat attached to them. Sometimes I even fell asleep watching that tank. Now it's empty, but I already have some plans for it.



fusiongt said:


> Just remember it's all about balance. In your last picture, it's obvious there was just too much lighting on as the plants were dense enough to make use of it + the CO2 = more algae. It happens... especially early on when the plants aren't established.
> 
> As for your large tank, just look at it as a new start. You have a large tank... going for cardinals isn't that exciting (at least not to me). Try a different breed... roseline sharks are beautiful for example.
> 
> ...


Thank you for your suggestion. Please be advice that I wasn't blaming "CO2 didn't turn off". But could that be affecting the whole situation? possibly. Like I said, fish seem ok at that time. I think I did a big mistake (which not sure what), before I left. But Mannnn, that's gotta be a huge since it takes less than 3 hours.



jeremyTR said:


> Ouch! I'd punch myself in the face if i ever did that to myself.


I hope that it would never happen to you.



AUvet14 said:


> Yup. I killed all of my amano shrimp that way. Cranked the CO2 up too much, say my rasboras huffing and puffing at the surface, turned CO2 down, then found all the shirmp dead later. :-/ It's definitely frustrating


Frustrating indeed. I wish that I came back when they're still huffing and puffing instead of floating around.



In.a.Box said:


> What kinda co2 setup was you using?
> 
> And that's ton of brown Algae my Otto will live happy with all that algae.


It's pressurized CO2. As for Otto on that algae, he only cleans up the rocks, but not on substrates and plants.




FlyingHellFish said:


> That happen to me once when my solenoid was unplug but kept pumping Co2 overnight. I had to blast out the dirt in the solenoid, it got stuck somehow.
> 
> Never buy those cheapo asian style regulators you see on ebay for cheap, I think they pump out a couple of working units and mass produce the rest.
> 
> I think the OP is using an Aquatek but I only hear good things about those.


Yup, that's what i was thinking. The solenoid probably stuck at night, but not sure how. Yes, indeed it is Aquatek, but honestly, I am not blaming on the reg. It's been working fine. It's probably my own fault.



plantbrain said:


> I nag nag nag people about CO2, instead they fuss and heehaw over ferts......I've never seen anyone kill fish with ferts, in 15 years...........
> 
> CO2? Every week a story like this.
> 
> I think many simply have to learn the hardest way. Or they give up.


The hardest way probably is the best way sometimes. As for "giving up", that word is not in my dictionary. 




jcgd said:


> Truth be told, I almost had this happen once but just before it was too late I discovered that I did in fact have cherry shrimp in my tank. I didn't know I had them in the tank (it was full of large rainbows) but when the co2 was too high they were the first to the surface, where I discovered them.
> 
> It looks like cherry shrimp can be somewhat early indicators.


You know, I had some RCS in there few months ago. They didn't last, but fish had been the happiest ever. I love that tank. It's like a complete eco-system. No issue.



mordalphus said:


> I think with some fish it's hard to tell when they're having a hard time breathing, so it's important when adjusting your CO2 to be around while it's adjusting. I usually do my adjusting on the weekend if my co2 is in need of adjusting for that reason.


Yup, that's exactly what I have learned the most. I was too OVERconfident that the whole setup would work perfectly fine. And I thought 3 hours wouldn't do anything. But man oh mannnnnnnnnnnnnnn, I was wrong.



josolanes said:


> Sorry about the losses *green_valley*
> 
> I nearly lost mine when I was in a hurry and unknowingly increased the co2 (quite a bit actually). When I realized it was too high, the diffuser was just pouring bubbles out - I've never seen that many before. And they were (mostly) being sucked in by my XP1's intake and mixed this way so much of it did get into the water
> 
> ...


Great thing there was no casualties. Good for you. Yeah, I probably did it in hurry. The thing is that I tested before I left. It was doing perfectly fine. Now, before I left, I had the timer on. So I had no idea what happened when it's on. I assumed that what I tested, was the output. I guess it wasn't.


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## chevyguy86 (Nov 12, 2011)

plantbrain said:


> I nag nag nag people about CO2, instead they fuss and heehaw over ferts......I've never seen anyone kill fish with ferts, in 15 years...........
> 
> CO2? Every week a story like this.
> 
> I think many simply have to learn the hardest way. Or they give up.


I hear ya on this, however I cannot seem to be able to get good ferts where I am, I have tried 4 times to get ferts shipped to me, and each time they where confiscated by Canada Customs, and yes I had a disaster with CO2, but now i have a PH Controller to monitor my CO2, and so far so good, I would never ever use CO2 again without a controller. The only ferts I can get are Fluval Root Tabs.


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## nameless? (May 28, 2011)

chevyguy86 said:


> I hear ya on this, however I cannot seem to be able to get good ferts where I am, I have tried 4 times to get ferts shipped to me, and each time they where confiscated by Canada Customs, and yes I had a disaster with CO2, but now i have a PH Controller to monitor my CO2, and so far so good, I would never ever use CO2 again without a controller. The only ferts I can get are Fluval Root Tabs.


Hydroponics stores have powered ferts, but you have to ask specially for kno3 since some regulation prevents them from having it on the shelves.


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## FlyingHellFish (Nov 5, 2011)

HD Blazingwolf said:


> in these cases i find flow to usually be the culprit, but i do use my oto's as much of my gauge. none of my fish ever surface when the are stressed. they just hide, and stop being active. and for my ottos i judge them differently. usually they are breathign rapidly. if i see them sitting in one place breathing really slow. i know its too high


Uhm, isn't it the other way around? They go up to the surface regardless, I'm guessing lower O2 will make them go up even more. If they're breathing heavy, and not active than I'm sure it's a sign of low O2.


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## green_valley (Sep 14, 2011)

FlyingHellFish said:


> Uhm, isn't it the other way around? They go up to the surface regardless, I'm guessing lower O2 will make them go up even more. If they're breathing heavy, and not active than I'm sure it's a sign of low O2.


That's what I thought too.


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## brainwavepc.com (Sep 27, 2011)

I don't think it's possible for my system to gas my fish. I use a pump to blow water down through a gravel vac tube while the air hose bubbles into it. I put a filter into the bottom to prevent any bubbles from escaping. If I crank the co2 the amount in the water doesn't change, it just displaces the water in the tube more and eventually just bubbles out. It's a very efficient system and was cheap for me to setup and I don't have to worry about gassing my fish. 

This is on a 125 with a ton of plants however so in a smaller tank or with less plants it might not be as foolproof, but it works for me.


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## green_valley (Sep 14, 2011)

brainwavepc.com said:


> I don't think it's possible for my system to gas my fish.


Well, I sure hope so. But that statement will never come in my mine after this incident. Anything is possible. Nothing is bulletproof.


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## brainwavepc.com (Sep 27, 2011)

Well I had a nephew turn the knob up where gas way pouring into my diffuser setup and I didn't notice until that night and fish were fine. So hopefully I'll be safe but that doesn't mean I don't keep a better eye on it now.


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## takadi (Dec 13, 2010)

It is amazing how little CO2 it takes for your fish to get gassed. I haven't gassed my fish yet but in one of my tanks I have two large HOB's and I can crank up the co2 with a reactor to three or four bps and the fish aren't even phased. However in my other tank, there is almost zero surface agitation AND there's a glass canopy over it. It's around the same size as my other tank and I was putting in less than 1 bps and when it got to 6 or 7 pm the fish were already gasping for air and their gills were fluttering like crazy. Luckily I caught it in time and put in a bubbler. I don't even use CO2 in that tank anymore and my plants survive almost perfectly with the CO2 that builds up from the fish.


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## brainwavepc.com (Sep 27, 2011)

Yeah good point, I run mine open top so that could be a contributing factor as well


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## flight50 (Apr 17, 2012)

I feel your pain. I lost 80% of my tank about a year ago. By the time I realized the problem I only had 20% of my tank left. I was using the Milwaukee co2 regulator with bubble counter and my co2 tank dumped. I now use the Aquarium Plants.com electronic regulator. Impossible to dump now and alot more effective. A bit pricey but well worth it.


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## green_valley (Sep 14, 2011)

takadi said:


> It is amazing how little CO2 it takes for your fish to get gassed. I haven't gassed my fish yet but in one of my tanks I have two large HOB's and I can crank up the co2 with a reactor to three or four bps and the fish aren't even phased. However in my other tank, there is almost zero surface agitation AND there's a glass canopy over it. It's around the same size as my other tank and I was putting in less than 1 bps and when it got to 6 or 7 pm the fish were already gasping for air and their gills were fluttering like crazy. Luckily I caught it in time and put in a bubbler. I don't even use CO2 in that tank anymore and my plants survive almost perfectly with the CO2 that builds up from the fish.


Agreed. It doesn't take too long for the fish to gass out. I usually have the CO2 running without surface agitation, then when the CO2 is off, I have the surface agitation. 




flight50 said:


> I feel your pain. I lost 80% of my tank about a year ago. By the time I realized the problem I only had 20% of my tank left. I was using the Milwaukee co2 regulator with bubble counter and my co2 tank dumped. I now use the Aquarium Plants.com electronic regulator. Impossible to dump now and alot more effective. A bit pricey but well worth it.



Thanks. At least you got 20% left, but still it's sad when you saw them died. In my case, I would not blame it on the reg. I would say it's my own fault.


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## Cardinal's Keeper (May 19, 2012)

Very sorry to read of your loss... 

Next time around with C02, possibly think of using a two way PH controller like the American Marine model if your budget allows. 

I have been using one for years and always keep an air pump plugged into the low side with an air stone connected in a corner beneath the substrate that I place at setup. Twice over the 8 yrs or so of using the controller, I have had solenoids stick open and the air pump will kick on once it goes below the low PH setpoint I have programed and offset the constant gas being pumped in long enough for me to notice and address the problem. 

Yes the airstone will muddy the tank and disturb all my substrate and plants in that area, but much better than the other outcome.


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## flight50 (Apr 17, 2012)

I think alot of us have done this. My incident happened over the course of a week slowly killing off half my tank. Then I realized my sub par regulator dumped the remains of my low co2 tank. It happens to the best of us. That's how we learn from our mistakes.


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## vraev (Apr 13, 2012)

I am truly sorry to hear this. Let me share a little unrelated, yet somewhat related story: I grow carnivorous pitcher plants and it took years for me to gather some very rare and expensive plants. These plants require cool night temps and as a student, there is only so much I can afford, so I used to use outside winter air to cool my plant tank down. The plants were growing amazing and I grew them from 1cm size. I grew seedlings that took 3-4 years to grow from 1cm to 2". But in one night, during January this year, I lost over 40 of my most beloved plants. Heck, I got into aquariums now as a way to distract myself over that loss. However, I still try to tag on with it and keep the survivors chugging along. It was a major blow and i lost almost a thousand dollars worth of plants. More than the money, it was the care and effort and the love I had for them. 

Bottom-line, [censored][censored][censored][censored] happens and we got to live with it and move on. It sucks, but the best we can do is keep this incident in mind and learn from the mistakes. Have failsafes next time. Maybe have some sort of mechanisms by which u can ensure adequate air intake into the tank. It may mean your plants have to grow slower due to in-efficient CO2 absorption, but its better than killing the inhabitants.


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## Tyger (Dec 9, 2010)

*Dude! Wow! Oh Man!*

Dude! Wow! Oh Man! At present, I run my CO2 on my 65-Gallon on the light side (rather too little than too much... plus I hate to trim all the time). I have a Victor (2-Stage) regulator. At present, I run CO2 overnight without an issue and have great plant growth. Again, I err on the light side when it comes to CO2 (always!). I had a solenoid though was not happen with it at all so I no longer use and I decided to save a little money and purchase a CarbonDoser Electronic Co2 Regulator (super precise bubble counter). Several members of our aquatic plant association use them with great success. Since the units are electric, they can double as a solenoid and do work with pH monitors/controllers. Once installed, I will save some CO2 and sequence it with the lights on timer.

In closing, I am really sorry to hear about your loss... that sucks beyond what words can convey. I am glad, however, to see your continue on... my advice besides saving for good equipment (name-brand, two-stage regulator, possible carbondoser, and maybe down the road a pH regulator.... do what seems so obvious now... err on the light-side when it comes to CO2. Oh, and rather than link tanks, I'd focus on the large one and use the above set-up for that... you might run a side-line to smaller one with a regular bubble counter and simple valve system down the road.

Anyway, I wish you the best...

~Tyger (Michael)~


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## Steve001 (Feb 26, 2011)

Tyger said:


> CarbonDoser Electronic Co2 Regulator (super precise bubble counter). Several members of our aquatic plant association use them with great success. Since the units are electric, they can double as a solenoid and do work with pH monitors/controllers.  Once installed, I will save some CO2 and sequence it with the lights on timer.
> 
> 
> ~Tyger (Michael)~


Nifty, but what happens if you lose power for an extended time ?


Recently my regulator I've been using for over 25 years has failed. It had a solenoid valve. Now I have a new one. This unit is very simple. It consists of a needle valve and regulator.


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## aquariummom (Apr 14, 2015)

green_valley said:


> Hello everyone,
> 
> It's been about 3 weeks now that this disastrous incident happened. I have finally "somewhat" moved on and am able to share the story. In the beginning of the month (April), I wanted to rescape my 50G tank (here is the journal: http://www.plantedtank.net/forums/tank-journals/156848-green-valley-goes-more-than-green.html). Even though the tank has been great since last year, I wanted something different.
> 
> ...


Dotto ditto I just lost all of my rainbows, neons, green cats, pleco, several others. Solenoid malfunctioned as I had it turned completely off. I am so shocked and sad. I am going to wait till CO2 is disipated with lots of aeration and re intro later. Wpw it was only 3 hrs I left the tank.


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## Argus (May 22, 2013)

aquariummom said:


> Dotto ditto I just lost all of my rainbows, neons, green cats, pleco, several others. Solenoid malfunctioned as I had it turned completely off. I am so shocked and sad. I am going to wait till CO2 is disipated with lots of aeration and re intro later. Wpw it was only 3 hrs I left the tank.


Condolences. What, exactly, happened? It might help others avoid such disasters. 

What CO2 system are you using? 

Was this an end-of-tank dump, or just CO2 being on all night?


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## co2art (May 28, 2014)

On page one, they said it was an aquatek but it was most likely user error.


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## lksdrinker (Feb 12, 2014)

co2art said:


> On page one, they said it was an aquatek but it was most likely user error.


LOL page one was written many moons ago!


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