On Sunday, my CO2 system seemed be be malfunctioning. I noticed no bubbles were coming out at the diffuser. The pressure on the second indicator of the regulator seemed low. Moreover the glass bubble counter integrated into the regulator had no water in it so I could not tell bbs. I lifted the tank and it was almost all full. I filled up the bubble counter and noticed it was leaking badly. Upon inspection, the o-ring had disintegrated. I decided time to order a new bubble counter. Meanwhile, I did not want to have CO2 swings, so I opened up the needle valve (also integrated into the regulator) to see whether I could increase the pressure at the diffuser to get some bubbles into the tank. It finally worked and I got a very small trickle come through. I left it at that and went to order a new bubble counter and a diffuser - just in case that was the problem.
Monday, I checked everything in the morning and evening. All is well. Tuesday I had to rush to work in the morning so I next checked the tank when I got back from work - I have an auto-feeder so I can skip my morning checks sometimes. The new diffuser and the bubble counter were waiting for me when I got home. I was eager to get the CO2 working reliably again since CO2 fluctuations can promote all sorts of bad things - plant growth issues, algae, etc. When I got to the tank, I noticed an Oto on the carpet. It was upside down and clearly dead. Otos are very sensitive to water parameters so I thought the CO2 fluctuations must be affecting the water quality somehow. At that point it occurred to me that there was a lot of uneaten food by the feeder. My 8 year old daughter who was there to help me said - "Dad, is that another sick fish?" One of my ember tetra's was at the edge of the carpet, also dead. Then I looked into the tank from the top. To my horror, a ton of dead fish was floating right by the intake. I looked around the tank and all my fish were dead - the plants were littered with dead bodies. I lifted the glass cover and a most foul smell came out. My daughter was very distraught - she kept on saying "dead fish look scary." My wife took her away. I started to explore what could have gone wrong. I checked the temperature: perfect. I opened the cabinet to get the test kit and when I moved the CO2 tank I started to figure out the culprit. The tank was empty. I took the regulator off and put it on my second tank - I always keep two so that when one runs out I don't have to rush out to get it filled. As soon as I opened the tank valve, CO2 came rushing out: sometime between Monday evening and Tuesday evening the needle valve had burst.
I lost 6 honey Gourami, 8 ember tetras, 8 rummy nose tetras, 2 peacock gobies, 6 panda cories and many amano shrimp. Many of these fish had been with me since I started with the hobby 3.5 years ago. The gourami were our family's favorite. They would often had paired up and moved around togehter, sometimes almost embracing. I was devastated. RIP fishes
For the next day I thought I'd leave the hobby. Or maybe just keep a plant only tank. But the tank looks so empty: it is almost depressing to see it with no movement. So I think I'll go ahead and order a new regulator and also a PH monitor to shut off the CO2 regulator if something like this happens again - though I am not sure how effective that'd be. I am going to wait for a few weeks before I do anything though.
PS: One thing did survive the carnage: Pest snails (mini rams horn in this case - the ones that are 1/4" in diameter). Yep, not only did they survive, they are thriving - there was a ton of rotting meat for them for 24 hours. I really think if there is a nuclear war the only things to survive will be cockroaches and pest snails.