NA Advanced Co2 Reactor | Advanced Version With By-pass Valve | Clear Reactor Chamber | Free Shipping

(5 customer reviews)

This style reactor is one of the most efficient methods for diffusing co2 and includes a clear reactor chamber so you can see the co2 being dissolved.  The advanced reactor with bypass is efficient for tanks well over 100 gallons and high flow filters such as fluval fx5/fx6.  The reactor is designed to be used between the canister filter and the tank on the output side of the filter.  It should be mounted under the tank and needs 18-24″ of vertical space.  Water should enter the top of the reactor and exit out the bottom.  If you have any questions about the use of this style reactor please make sure to contact me prior to purchasing.



Add Accessory Kit?

(Hose Clamps and Stainless Check Valve)

2″ PVC pipe straps to mount reactor to wall or aquarium stand


The major advantage of this style reactor, other than near 100% dissolution of co2, is that they require almost zero maintenance and nothing visible in the tank.

When ordering please choose the tallest size that you can fit under the tank, the taller/longer the reactor is the more co2 it can efficiently dissolve.  Also make sure you confirm the inside diameter of the output tubing on your filter.

The actual length of the reactor will be +/- 0.5″, if you have a very tight fit please let me know prior to ordering

Note:  For people with higher flow filters which use 1″ tubing such as the fluval fx5/fx6 filters, I would highly suggest choosing the 24″ long reactor.  People using the fx4 would still be best choosing the 24″ version but can get by with the 22″.  The reason being the longer reactor can handle higher flow.

Color of the reactor:  The standard color is black.  I can paint it other colors for an additional cost.  If you would like a different color, be sure to check that option above then please include the color which you would like it painted in the comments section while checking out.  Please only standard colors, I will do my best to match the color that you want but I can only guarantee that it will be close.

Setup Instructions:

-Mount the reactor vertically(long side up)

-The water should enter the top and exit the bottom

-Start with the valve closed(parallel to the ground)

-When all the hoses are connected(filter and co2) run the reactor for 24 hours before making any changes

-If after 24 hours you are getting co2 bubbles out of the return pipe, open the valve slightly, then wait for 24 hours

-Repeat the previous step until you are no longer getting co2 bubbles pushed out of the reactor




*Shipping for Rex Grigg reactors is via FedEx or USPS ground shipping

*Because the Rex Grigg reactor is a custom build piece there is a 1 week lead time before these will ship.

Additional information

Fitting Size

1/2"(12mm), 5/8"(16mm), 3/4"(19mm), 1"(25mm)

Reactor Length

24" Tall, 22" Tall, 20" Tall


  1. Ian (verified owner)

    This reactor does exactly what it is supposed to – CO2 is completely dissolved in the reaction chamber before it enters the aquarium. Much more efficient than a diffuser. My 24″ version is hooked up to a Fluval FX6. Attaching the reactor to the filter was a breeze – just be careful to check for leaks at the attachment points between the reactor and filter hose. Initially I re-used an older rubber connector and it leaked even with hose clamps. The problem was fixed when a new connector was used. The reactor itself works flawlessly. Great customer service as well.

  2. Dan (verified owner)

    100% dissolution. Works perfectly, adjust the valve until you see no more bubbles from your outflow and you know all the CO2 is being dissolved. It is solidly built, honestly probably better than I could have done myself. You may be able to build it cheaper yourself, but you have to find your own parts, paint them, put them together so they don’t leak etc… In the end it came down to convenience and quality, and buying this reactor has both. Would recommend buying the largest reactor, I have it on a 30 gallon tank now, but you can move it to a larger tank in the future and know you’re covered. To sum it up, I say buy it and enjoy having the best prebuilt reactor available.

  3. Ivan (verified owner)

    The Na Adv. Reactor is a must for your planted tank.No soda bubbles,great diffuser,minimum maintenance,semitransparent middle tube for bubble counting.Love it!

  4. Matt Wohlford (verified owner)

    I’ve dabbled with different forms of co2 dispersion including diffusers, atomizers, and even a smaller reactor. This Reactor hits the mark. I have this setup on my 55 gallon planted tank. I would recommend buying the longest length if possible (I went with the 24″ tall version) and I have absolutely no co2 bubbles coming into my tank -so there is some quality diffusion going on.

    It is also nice that middle tube is semitransparent, you can make out the co2 bubbles being injected, so you don’t really need to use a bubble counter. It would easier to see if the tube was clear, as it would be easier to count, but this is a minor complaint.

    Build quality is solid.

    No regrets with this purchase, it should “travel” around to many different tanks for many years to come.

  5. Ryan Alfredo

    Up until this point, I have been using the atomic atomizers to diffuse CO2 into my aquariums. These work great but I found that I was wasting CO2 in the form of bubbles which rise to the surface and pop. Also, the bubbles make the water look like soda water, which I like, but it does cut the visibility down and taking a clear picture of the aquarium is impossible unless you shut the CO2 off.

    I got a 150-gallon tank and decided to try something new regarding CO2 diffusion. I found out about this reactor (ADVANCED CO2 REACTOR) and decided to give it a go. Colin from NilocG aquatics was fantastic. He helped me get set up and answered all my questions.

    This device literally diffuses the bubbles into the water until there is no bubble left. The only bubbles you will see are the oxygen bubbles streaming from your plants. Had I not seen the bubbling plants, I would not know there was co2 in the tank! This makes it 100% efficient and allows me to lower my bubbles per second significantly.

    I used to have to disconnect my old atomic diffuser from my filter tubing every few months to clean the clogged ceramic pores. I don’t think this device needs any kind of maintenance so that is a HUGE plus. That was always a real pain. I am happy to cut that out of my routine.

    The clear nature of this reactor is nice because you can see if bubbles are getting close to the bottom(exit) and open the valve a bit to ease the water pressure a bit and keep all bubbles in the reactor until fully diffused. Being able to see this happen before my eyes is fantastic!

    Honestly, I am thinking of adding these devices to my other aquariums eventually so I don’t have to run through as much co2. I would recommend this to anybody looking to get more efficiency out of their pressurized system and lose the soda water look. It is fantastic!

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