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4"x28" Rex Grigg style reactor

Discussion in 'CO2 Enrichment' started by chrisaggie, Oct 4, 2017.

  1. chrisaggie

    chrisaggie New Member

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    I have been out of the planted tank hobby for many years and am in the process of setting up a 205g tank (36"x44"x30"). I plan to start a separate build thread shortly also. After reading quite a bit of this forum it seems like one of my main challenges will be dissolving enough CO2 into 205g + ~50g of sump water. It seems like some guys that started out with 2" diameter Grigg reactors upgraded to larger diameter reactors to be able to dissolve more CO2. I picked up a really nice Matheson dual stage regulator and Ideal needle valve I plan to run on this reactor through my return plumbing. The reactor is make out of 4" diameter PVC with a small clear section so I can see what's going on inside and is a total of 28" tall. I guess I will need to run 5-10 bps on this tank. I have no experience with Grigg style reactors and would love some opinions and thoughts on this setup. I figure if I have to I can always add another reactor (but went big from the beginning and hoping this one can handle it).

    Rex Grigg reactor.JPG
     
  2. burr740

    burr740 Micros Spiller
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    Hi Chris, welcome to the board.

    Fatter is better than skinny, you're right about that. I'd imagine that one can handle a lot of co2 and flow, but you never really know until you try it.

    Is the middle port where the co2 goes in? im wondering if that might be too low. (purely a guess)

    In the the traditional Griggs design thats about where the co2 goes in, but one of the key points is using the under sized hole and poking the tubing through so that the co2 bubbles enter the chamber in the center of the water column. The bubbles have a stronger floating capacity than when the co2 enters on the side edge. Coming in from the edge they tend to slide right up the side and dont really fight against the current like they would entering in the middle.

    Ive never used the traditional design because I dont trust the undersized hole not to leak. But I have built a few similar to this one and found that its better for the co2 to enter at a higher point.

    But it might work just fine. The good news is you can always cap the middle port off and run the co2 right before the reactor, like this 3x24 I use for my 120 gal.

    30916703000_d25481d8f2_c.jpg


    But I would certainly try it first and see, might work great the way you have it
     
  3. chrisaggie

    chrisaggie New Member

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    Thanks for the thoughts/advise. Yes, the middle is meant to be used for the CO2 injection point. I will try to come up with a small tube than sticks into the middle on the 4" pipe so the gas bubbles in the middle and not up the side as you suggest. If all else fails I will inject at the top as you have.
     
  4. burr740

    burr740 Micros Spiller
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    Keep us posted how it goes. im always curious about reactor designs
     
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  5. chrisaggie

    chrisaggie New Member

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    I plan to run this inline with my return pump currently as one of my main goals with this tank is to keep it as energy efficient as possible and I cringe at the thought of having to use a separate pump for this just to dump it back into the sump. My main plumbing will be 1.25" PVC and the tank top will be at ~60" off the floor. Is it a mistake to try to run this through the return plumbing?
     
    #5 chrisaggie, Oct 5, 2017
    Last edited: Oct 5, 2017
  6. chrisaggie

    chrisaggie New Member

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    It took a bit of dremmel work with the pvc connections, but I rigged a 1/2" pipe sticking into the middle of the reactor so the CO2 bubble will be injected into the flow and not up the side. The 1/2" pvc is capped inside and a small hole drilled into the top of the pipe. My thought here was to make the hole in the 1/2" pvc bubble and not release big pockets of CO2 all at once inside. I realize it may be a mistake, but I am going to try to run this reactor through my return plumbing and not on it's own loop. I will use unions on the plumbing so I can always redo it fairly easily later.
     
  7. chrisaggie

    chrisaggie New Member

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    Oh my! I finally got the reactor and all the plumbing done and the tank filled up for a test run last night. As you can see in the picture attached (from back of tank), I did decide to try to run the main return line through the reactor (which looks like it will be a good choice). The pump is a Jebao DCP-6500 which is pumping roughly 700-800gph through 1.25" plumbing. It took the reactor a little bit to push/dissolve all the air which was in it and it was a tornado of bubbles inside the reactor. I have a feeling this thing will be able to handle a lot of CO2. I will give another update and try to take a video once I get it up and running with CO2.

    205g plumbing back.JPG
     
    Greggz and burr740 like this.
  8. chrisaggie

    chrisaggie New Member

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    I finally got CO2 running through this thing about a week ago. I have the CO2 running at 6-8 bps currently and the reactor has absolutely no problem keeping up with that. I did have to to turn my main pump down a little because the water flow was too fast through the reactor. I installed a bypass valve I plan to play with so I can turn the pump back up and have some of the water bypass the reactor. I also plan to turn the bps count up a little more but have no doubts that the reactor can handle it. I will try to post a video in the next week or so. I'm gonna use the slow motion function on my phone to try to get a better bps count also.
     
  9. slipfinger

    slipfinger Article Editor
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    How does your Co2 enter the reactor? Is there something that extends inside the reactor so the Co2 enters the middle of the reactor?

    My current design just enters the reactor throw a barbed fitting. What I find is the Co2 just slips up the side wall of the main chamber and starts to collect at the top of the reactor. My new reactor for my new tank has a 1/4" piece of rigid tubing that extends far enough into the reactor so the bubbles are entering the middle of the reactor and hopeful the middle of the water stream.

    35941927201_88580b3d9d_c.jpg
     
  10. chrisaggie

    chrisaggie New Member

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    Yes, I rigged it so that the 1/2" pvc that the CO2 is injected through extends into the reactor with a small hole drilled in the middle that all the CO2 is injected through. Honestly I don't think this matters as much as the high flow though but I would have to play with the injection spacing to prove or disprove this theory. I will try to draw up a little sketch of how I built it in case it would help someone else out in the future.
     
  11. slipfinger

    slipfinger Article Editor
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    I'd be interested in how you have the Co2 enter the actual main chamber.

    Thanks
     
  12. chrisaggie

    chrisaggie New Member

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    I made a quick drawing to show how I constructed the reactor. The biggest trick was to dremel out the 1/2" pvc coupler and slide the 1/2" pvc all the way through it into the middle of the reactor. HP0212.jpg
     
  13. slipfinger

    slipfinger Article Editor
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    Thanks for the diagram.

    This is the exact flaw in my current design. I do not have the 'extension' which allows the Co2 to enter the middle of the water stream....

    As mentioned I think my Co2 is just slipping up the side of the main chamber and collecting at the top of the reactor. I get a decent pH drop but I'm sure it would be more efficient if the bubbles actual entered the main stream of water.
     
  14. chrisaggie

    chrisaggie New Member

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    I feel like I have really put the reactor through its paces now! Over the last several days I have slowly upped the CO2 to 16bps (used the slow motion video feature on my phone to count). My drop checker has started turning green at this rate but is still blueish green. The reactor is having no trouble with this high rate. I may turn the reactor up a little more but want to give it a few days running at 16bps first.
     
    #14 chrisaggie, Dec 24, 2017
    Last edited: Dec 24, 2017
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