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Will this DIY external reactor work? I hope so...I already built it !

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  • Will this DIY external reactor work? I hope so...I already built it !

    Hello all,

    I was wondering if you all could share your opinions about my new DIY external CO2 reactor. I plan to run this on the output of my Eheim Pro3 2071 (250gph) and then through an Hydor external heater and then up to my spraybar. I also have a Korilla Nano on order to help with flow inside the tank. By the way the tank is 33 gallons (25"x18"x18")

    I found a similar design for a reactor on the APC forums from a few years back and thought I would try to copy that design.

    I am probably being too paranoid about leaks, but I wanted to put a check-valve before the Co2 line so that in case that little tubing was to ever come off, then no water would leak out of the reactor. I obviously wouldn't want any water to get to the regulator, but it was a larger concern to me that no water get out on the floor in the event of a catastrophe. So that black plastic part on the CO2 inlet is a check valve.

    I also like the fact that this design has a way to purge air or co2 build up at the top of the reactor (that is what the red handle ball valve is for). I want to mount the reactor to the wall of my cabinet so I wasn't too thrilled about having to tip it upside down to get out trapped air when trying to prime the filter. Plus I want to keep the hoses as short as possible and if I needed to turn the reactor upside down when priming, then that would mean longer hoses would be needed. you all see any major flaws in this design?
    It has 5/8 barbs connected to the Ehiem 16/22 tubing. That 5/8" goes down to 1" where the water and Co2 make first contact. And then the reactor tube is 2" diameter and 10" long and the entire thing is about 16" from barb to barb.

    I really wanted to use plastic hose barbs instead of brass, but I can't find 5/8" plastic barbs anywhere (let alone 16mm to perfectly fit the Eheim tubing). If anybody can provide me a link where I can order them I would be MOST appreciative.

    Thanks in advance for any input !
    Last edited by bill321; 05-21-2010, 06:35 AM.

  • #2
    Leaks Happen

    Hi Bill,

    No such thing as to paranoid, well okay maybe there is but in the case of leaks, failure is always an option.

    It looks like a very nicely constructed reactor it should work fine.

    Try Tru Value Hardware or Home Depot for barbs and such.

    Remember just because you are paranoid does not mean they are not out to get you!

    The first sign we don't know what we are doing is an obsession with numbers. - Johann Wolfgang von Goethe

    Disclaimer: I am not trying to make you mad, it is just what I am, an evil plant monster, 'nuf said.
    • I believe the information I am giving is sound, I am not a veterinarian, professional chemist or particularly bright and certainly not a "Guru.".
    • I assume you are of legal age, competent and it is legal for you to acquire, possess and use any materials or perform any action in your in your jurisdiction.
    • When in doubt "don't."


    • #3
      OK......I changed the design slightly.

      I have the CO2 coming in on the side now.
      And I also used plastic barbs so that no Brass ever touches water.

      What do you all think of revision#2 ?
      Any better?

      I like the idea of the check valve where the CO2 enters the reactor so that no water can escape and only CO2 can enter. But I wish I could inject the CO2 into the chamber as a small bubble.....I suspect this is going to produce large bubbles that rise to the top. I wish I could have found some clear PVC so I could see what was going on inside there



      • #4 has clear and transparent PVC as well as clear fittings.

        Aquatic Eco-Systems does too.


        • #5
          I would recommend a hose fitting or something off the ball valve for when you purge it. It'll give you somewhere for the water to go when you inevitably don't close it off fast enough. Not that I'm speaking from experience or anything like that....



          • #6
            Instead of using a 90* elbow at the top for your water inlet, just use a straight "T" connection so the water flow is straight down all the way to the bottom. The flow will be fast enough in the smaller diameter pipe to keep the bubbles in the reactor below it.
            "Do, then talk about it.
            No do? No talk!!" - Tom Barr


            • #7
              This is hopefully my final revision

              OK...I tried to incorporate all the good advice I was given and this is what I came up with.

              This revision has a way to eject CO2 into the column of water in the reactor as a small bubble (I hope).

              I found a PVC cap at Home Depot that fit the inside of the coupler where the CO2 will be injected. I drilled a small hole and pulled through some of the CO2 tubing and it is snug enough so that it will not move. This should allow the CO2 to come out as a 3/16" bubble right into the middle of the water column. The way I did it before would have probably made a 1/2" bubble.

              I also got a small hose barb to attach to the Bleeder-Valve at the top. I figured that way I could run a hose to a bucket when I am trying to get air out of the reactor when I prime the filter.

              What do you think of this design?
              Any major flaws?