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CO2 Dump!

October 20th, 2008

CO2 Canister & RegulatorAfter the catfish convention auction, I came home and started acclimating the new bristlenose plecos that I got. I putting them in a 20L quarantine tank, and when I turned around I noticed that none of the sunfish or killies that usually swarm the front of the tank were there. Eventually, I spotted a few of the sunnies dug into the Ranalisma rostrata, and a few others swimming awkwardly at the water surface.

Immediately, I knew what had happened; the CO2 tank ran out, and dumped a ton of CO2 into the aquarium all at once. Right away, I pulled out my Python hose, and did a 50% water change. I also borrowed an air pump from another tank, and threw an airstone into the 40G. At that point, all I could do is wait and hope that I wasn’t too late.

I’m happy to report that despite some really dire looking fish, nearly all of the fish survived as of today. I only have one sunfish confirmed dead, and all killies are accounted for. I was lucky.

So, now the question is what can I do to prevent this from happening again? Well, two things come to mind:

1. I could add a pH controller to control the solenoid on my CO2 tank. If the tank suddenly started dumping, the pH controller would shut off the flow of CO2 once the pH dropped below a certain level. Unfortunately, this is not the cheapest solution.

2. I could attach a low-pressure regulator to the regulator I currently have. This would detect the low pressure that causes a CO2 dump, and vent that gas to the room, instead of the aquarium. The downside to this is that I already have a 3-way manifold on my regulator, which is pretty heavy. I’m not confident that the low-pressure regulator could support that weight.

So, I’m not sure what I’m going to do. At this point, I should have at least 6 months to decide before this could happen again. It’s not even a guarantee that it will happen again. That said, I don’t want to take any chances. Does anyone else have any alternative suggestions for what I could do to prevent this from happening in the future?

12 Responses to “CO2 Dump!”

  1. m@ Says:

    I’ve never put CO2 onto my tanks, but I do controls on a larger scale for work. Why would running out of CO2 dump CO2 into your aquarium and how would a regulator help?

  2. Adam Says:

    You could try 3 Ideal 52-1-12 Needle Valves
    I believe I saw somewhere that they work well against end of tank dumps. They are not cheap though.

  3. Chris Says:

    I had this happen to me once, luckily I had no fish in the aquarium at the time

  4. guitarfish Says:

    m@, from thekrib, this is what causes the dump:

    When the input
    pressure to the regulator decreases, the output pressure *increases*, at
    least until the output pressure equals the input pressure. (At that point
    the regulator essentially becomes an open valve.) That is what causes the
    “dumping” when your tank runs low.


  5. guitarfish Says:

    I just came across another potential solution for my particular Milwaukee regulator:


    Basically, I need to set my low-pressure gauge higher than I have it to minimize the end-of-tank-dump problem. Currently, it’s set right around 20psi. I’m going to try increasing it to 30-35psi, and see how that goes. If that fails, I’ll investigate The Ideal 52-1-12 needle valves, but I’d rather not drop that much cash on those right now.

  6. m@ Says:

    Hmmm, that doesn’t make sense as flow through a given orifice should increase with a rise in the pressure drop. If your tank is running out that should lower your pressure drop. Maybe these regulators are designed to require a minimum pressure differential across them. That’s unusual though.

    Drop me a message if you need needle valves. I can check to see if I can get them any cheaper.

  7. guitarfish Says:

    I haven’t a clue with this stuff, m@. The two URLs I referenced above have some folks talking more in depth. I’ll let you know about the needle valves if I have another dump. Thanks!

  8. Eugene Says:

    Nice article. Thanks. 🙂 Eugene

  9. thick Says:

    what did you do?

  10. guitarfish Says:

    Thick, so far I just upped the pressure as recommended in that plantedtank thread in comment #5. So far, so good.

  11. Justin Says:

    Would having a dual stage regulator prevent dumping?

  12. guitarfish Says:

    Justin, yes, the dual stage regular does prevent dumping.

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