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xdestry 10-11-2012 09:54 PM

Gassed my entire tank!
Hey guys, so I gassed my entire tank this morning! Never thought it would happen to me but here we are. Not everything was lost however as I got there in time to save the rest but I lost a couple fish and shrimp.

As soon as I woke up this morning I knew I had forgotten to turn off the co2. Forgetting to even put on my glasses, I ran to my tank and saw a faint blur of fish thrashing on top. I turned off the co2 then ran back to my bedroom to put on my glasses. When I got back to the tank I saw that the faint blur was my pseudomugil furcata thrashing around on top, I have not seen a fish thrash like that except when I had to cull a fish using a carbonated water method I read about online. I looked around and saw the female furcata thrashing around as well, a boesemani rainbow was lying sideways on the surface, my gertrudaes were huddled in a group gasping for air, and I saw an oto cat swimming around upside down on a bed of hairgrass. My zebra danio however was totally fine just going around his day, probably wondering why everybody else was acting so weird.

I looked down and saw a graveyard of shrimp but also a few that still looked alive but not moving. My only tiger shrimp I had left was dead, as well as a few "mystery shrimp" (the term I gave to a birth of shrimplets which I have been unable to identify, I thought they were tiger shrimp originally but no stripes have come in after a month and I am now thinking they might be a wild colouration of neos.) I found a snail that had crawled out that dropped him back into the tank, hoping he had not dried up yet. I then immediately started netting the fish out and transferring them to my other tank nearby, they showed immediate improvement and stopped thrashing around.

I raised the filter outtake to get some air into the water then took out 30 percent of the water for a change. I took out another 30 after that and replaced it again, and finally took out another 30 at the end to give the filter outflow some room to fall. I took a few amanos that were very still and transferred them to the other tank as well. By now there was not much more I could do so I started watching the fish in the new tank, which seemed to be floating very still on the surface. Now about an hour later they are still floating on top, but I think they are going to be okay. The amanos I took out are also all alive now but still acting abnormal. In the gassed tank I looked around and counted around 8 shrimp dead in total. One oto cat also died, and many are still very still. I am lucky I got there in time however and did not lose everything like many people have. I will definitely be paying more attention to turning my co2 on and off now after this incident!

Anyways I just wanted to write this as a reminder for everyone to be careful with their co2. Going up to a tank and seeing your fish and shrimp all dead and dying is a horrible sight and I hope nobody else has to go through this!

tetra73 10-11-2012 10:03 PM

The question is how is your CO2 system being setup? At night, I have an air pump turned on until 30 minutes before the CO2 comes on. My soleniod is connected to a timer. If the either the timer or the soleniod stopped working, the air pump should be enough to prevent massive gassing. There was a week my CO2 was turned on for 1 hour at some times around 1 am because I have accidentally pushed in one of the tabs on the timer. I didn't notice it for about week until I actually checked the timer.

pejerrey 10-11-2012 10:09 PM


you have no solenoid?

Buc MacMaster 10-11-2012 10:10 PM

Good job on the save, but I don't understand. My CO2 runs 24/7 and the fish are fine.........never a sign of distress of any kind from the angels, the corys, the otos nor the guppies. The plants grow, the fish eat and the CO2 runs. Am I missing something?

tetra73 10-11-2012 10:17 PM


Originally Posted by Buc MacMaster (Post 2040369)
Good job on the save, but I don't understand. My CO2 runs 24/7 and the fish are fine.........never a sign of distress of any kind from the angels, the corys, the otos nor the guppies. The plants grow, the fish eat and the CO2 runs. Am I missing something?

It depends on the amount of CO2 you are injecting. What is the color of your drop checker? Mine is deep yellow by the end of the light cycle. 24/7 CO2 on my part without at least an air pump at night? I will see dead fish in the morning for sure.

HD Blazingwolf 10-11-2012 10:37 PM

co2 is the killer

the silent killer is oxygen levels
i firmly believe this and this is why i happily run my wet/dry sump setup now. i inject what on my cannister would have been lethal, now only is slightly stressful if i make a mistake
its still possible to kill my fish with co2, but i have more room for error, and its VERY apparent. GOOD surface agitation and clean filters, plus good water chagne habits and happily growing plants will rpevent many of these problems
for reference, my dc is yellow 2 hours after co2 is on, not by the end of the light cycle. it stays that way all day, and when i get close to end of tank my working pressure increses 2-5 psi depending on ambient temperature and fish still are fine

pejerrey 10-12-2012 01:31 AM

I also believe that with good aeration by surface agitation by a spray bar or surface skimmer or an airstone.

This thread is a good read to understand why we can suffocate our pets:

Next time, take seriously the fact that you can kill them. Choose a way to do it that is not at the edge of a catastrophe.

My condolences. :(

oscarsx 10-12-2012 02:48 AM

This is my concern and worries also, I always have my powerhead pointing towards the top of the tank for extra water movement :)

Java Moss 10-12-2012 02:50 AM

Let that spraybar splash the water's surface real good. Can never have too much of that, IMO.

My toddler got a hold of the timer that runs the CO2 solenoid and it was running full time without my knowledge a while back. Water was foggy, plants were bubbling like crazy, yet no deaths or fish freak outs. It was the spraybar that held down the fort!

And yes, he got popped on the behind for that little caper. Told the tyke a hundred times to "stay outta there!"

C.Barb. 10-13-2012 02:04 AM

Yea I've done that a few times on accident . Haven't lost anything thank god .... I have a blue ram who seems to be more sensitive than all my other fish ... So in order to accommodate him I run my co2 less .

senior el roboto 10-13-2012 04:33 AM

My co2 runs 24/7 also and no problems there. All my discus, rams, tetras ans coris seem to be just fine. I did almost gas everybody one time. Came home from work to find the valve had been opend up way further than it needed to be. My checker was bad yellow. All fish huddled on the ground gasping. Airstones and water changes later everyone was back to being happy.

shrimpedout 10-13-2012 04:52 AM

Well at least know suffocating isn't painful, just scary, especially for a fish. I'm glad most of them made it tho!

Get shrimped out!

fusiongt 10-13-2012 06:21 AM

It's worry some that you're trying to turn off the c02 by hand every night and on every morning? That's more work than owning a dog lol. Open up the wallet and get a timer (and solenoid if you don't have one) and have c02 as one of those "set it and forget" setups.

But like others said, the real problem is probably your c02 is too high if it's killing your fish at night when plants are producing oxygen. There's no reason for it to be that high; it should be able to run 24/7 without killing them. I prefer to save the c02 so I time it so it's on when the lights are on, but even if I run it 24/7 at that level my fish are fine. (Shrimp on the other hand I have in a low tech tank)

SlabMonster 05-06-2015 12:46 AM

I just had a terrifying experience with my 29 gallon! The timer on my solenoid turns on at 2:15pm, my lights turn on at 2:45pm. Earlier this morning, I was fiddling with my needle valve, and I guess didn't crank it back down enough. At 3:40pm I look over to see one of my crystal red shrimp down on his side aimlessly waving his legs. I tried to fish him out, but he swatted himself under a log. At 3:45pm, I notice two more doing the same thing. I would understand losing one shrimp, but three?

I immediately pull them out and put them in a container with some highly oxygenated water from my hospital.. uh.. bucket. I have a 5 gallon tank that was set up just a couple days ago, so the bucket was the best way to not poison my fish. The hospital bucket houses my beautiful German Blue Ram, who was attacked by a horrible silver molly that came with the 29 gallon tank a few months ago. (If anyone in Tucson wants her, let me know, right now she's cycling the 5 gallon tank.)
As I finish pulling out my third shrimp, thinking that there's a parasite or bacteria, a fourth one lands on its back too. Now I'm really freaking out. And all my fish are at the surface...

The CO2!!!! expletive Expletive EXPLETIVE!
I turn the CO2 off and fish out my other shrimp. I grab Pepe, the most peaceful dwarf puffer in the entire world, who was passed out in a corner, and toss him in the container with my weakened and near dead CRS.
I did a 10% water change, grabbed the air stone from the hospital bucket, and tossed it into my main tank.

Within 10 minutes the shrimp were all standing correct again, and Pepe was swimming along peacefully.

They're all back in the main tank now, at 5:30pm, looking much better and eating again. It was almost a disaster. My heart rate finally went down after many drinks of sake and watching them all eat and swim around normally. Funny, the crisis is the only time I got to see my blue velvets at all, as they swam around frantically in distress.

Kntry 05-06-2015 12:57 AM

I'm glad you saved them. I did the same thing about a month ago, trying to edge up the CO2. Tons of air and 75% water change saved them.

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