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Roughly how long should my CO2 tank last?

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  • Roughly how long should my CO2 tank last?

    I have a 72G tank and I am using a 5 pound CO2 tank. To keep my drop checker green I need to run at about 10-12 bps for the 12 hours my light is on. My CO2 tanks seem to be lasting only a month before refilling. I was under the impression I should be getting 3-6 months supply from this size tank



  • #2
    Hi Fred,
    A month sounds about right for that size tank. Just get a bigger bottle and it will save you the hassle in the long run. You can also squeeze a bit more service out of a bottle if you shut off the gas a few hours before lights off.



    • #3
      I get about 2 months with a 5 pound bottle on a 45 gallon tank, so I think you are getting about the right amount of time. CO2 isn't expensive, it is just inconvenient to get. That is a good reason to use the biggest bottle that will fit where you put it.


      • #4
        Thanks, at a minimum I'll get another 5 lb and swap them out. As always appreciate the replies and help



        • #5

          I have a 180g and a 10 and 5 lb bottle that I use and switch when one empties.

          10 lb lasts about 4-6 weeks (or less) for me to keep at 30 ppm c02...... I wait till both are dry and fill at the same time.... as it is inconvenient as Vaughn mentioned.

          FYI - I bought the 10lb pre-filled USED from the fire extinguisher place that does my refills for about $55. Much less expensive than new, but uglier/older.

          I would use a 20 lb, but does not fit under the tank

          I am going to buy another 10 lb next refill, and use the 5 lb for a smaller project, and swap between the two 10 pounders....

          Good luck. Hope this helps.
          Last edited by Gerryd; 11-19-2007, 10:30 PM.


          'When something's not right, it's wrong'. Bob Dylan

          Current 220 scape


          • #6
            Does a C02 tank have to be placed vertical? Mine is, just wondering.
            29 gallon - High Tech C02 enriched.
            50 gallon - Medium Tech, with C02.
            500 gallon Pond - Natural.

            See my Blog for Tank Spec's

            12 Steps on how to change plain gravel to a low cost sand substrate with nutrients

            How to Move with Fish, Tank, & Plants, 2200 miles


            • #7
              Yes, it will not work properly on its side.



              • #8
                I live in Alabama, so I'm not sure if you guys have this place where you live, there is a Place called Airgas. Its a medical/welding supply place. They refill my 10lb tank for only $22.50. $55 dollars sounds kinda high for a refill.

                I have a 120 Gallon and I'm running my tanks at around 10 bps. I have one of those powerhead reactors. Does that sound about right? My 4KH drop checker says so, but I'm always skeptical.


                • #9
                  I think he was referring to the bottle and the gas together that he bought for $55. But you peaked my curiousity. How much do you guys all pay for your refills? I want to go with pressurized CO2 but I don't want to pay $22 a month. I use excel now and only pay about $22 every 3 months and thats doubling the dosage.
                  Lucas Streit
                  Standard 75 Gallon Low Tech
                  Standard 75 Gallon High Tech


                  • #10
                    You should be able to find a filled tank in the $60 range. Check with local welding shops, soda distributors, fire extinguisher maintence houses, and any place that sells beer by the keg. Many places charge the same to fill the tank regardless of size, so it all depends on how big of a co2 tank you can keep. Measure your stand and just ask these places for the biggest tank that will fit, but remember to leave room for the regulator. You'll need about 5lbs a month for your 75gallon tank. A good reactor and turning off the gas a night might make a 5lbs tank last 5-6 weeks.

                    $7 a month for excel is pretty good. At that price the ROI of going co2 might be a long time.


                    • #11
                      I have been looking into setting up a CO2 system. The local fire extinguisher shop I checked with will sell me a refurbished hydro tested 10lb steel tank for $55. They charge $11 to refill it.


                      • #12
                        The short answer: it depends.

                        It depends on the size of the tank you are supplying with CO2, how bright the light is (which puts demands on amount of CO2 needed). And how efficiently you diffuse the CO2 into the tank. Less efficient diffusion typically means wasted CO2 gas escaping, and therefore you need to supply more.

                        I have been using a 5lb tank, making LOTS of mistakes as I learn and experiment. I've had a 5lb last as little as a week (leak in DIY bubble counter) on a 5.5g tank, and up to a month on a 20-long (slow leak in tube going to diffuser). Apparently, from others here, a 5lb on a ~20 gallon typically lasts roughly several months.