DIY Co2 reactor - The Planted Tank Forum
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post #1 of 8 (permalink) Old 02-16-2011, 03:28 AM Thread Starter
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DIY Co2 reactor

I am currently using one of those cheapo green "reactors" the sell online that they import from China. I'm semi satisfied with them, but they are made with extremely low quality plastic, so after adjusting them, both elbows split and the caps have sprung a leak. Tons and tons of teflon tape have made them workable but I wanna look for a better alternative.

I wanna make a DIY reactor but I'm not very handy and don't know where to start with parts. I'm guessing first I would need a cylinder, preferably clear. Then I would need to areas on the top and bottom for the water to flow in and out and an gas input somewhere. Don't know if I want a vortex reactor or something with media in it. I just want something that does the job, is easy to put together/take apart, and most importantly, is easy on the wallet
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post #2 of 8 (permalink) Old 02-16-2011, 04:49 AM
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It's quite common to make one from a gravel vac uptake tube and a powerhead attached at the top, (on the side so it spirals in (like the cheap green ones)).

I was never really happy with the one I made so I bought a cheap green one myself just recently, if I were you I'd keep the top of the green reactor and try to replace the bottom part with a longer clear tube from the gravel vac, drill a hole in the side and use a micro diffuser inside the cylinder and at the top of the green reactor hook the old inlet tube back into the powerhead so it chops up any large bubbles and puts them back into the reactor.

I will be doing this when I finally break my green reactor (which is mounted inside my tank).
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post #3 of 8 (permalink) Old 02-16-2011, 04:07 PM Thread Starter
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My reactor actually came with a nice little diffuser. I swear there must be a company that makes all this stuff because if you order more, you can connect the parts to make the reactor cylinder longer.

How mine is set up currently is that the diffuser and the cap where the diffuser is connected is at the bottom. It came with one of those "bioballs" too. The water flows in from the top and spins the bioball around in a vortex. The bubbles get chopped up and flows out the tube on the bottom. Luckily, the diffuser end sits high enough so that the little bubbles float to the top to be chopped up by the bioball instead of immediately being sucked out the bottom. I was fortunately able to buy large enough tubing my from LFS.

I am just PO'ed though that the elbows split so easily. I have mine mounted outside of my tank, so I have to make sure there are no leaks. Lots and lots of teflon tape...I must have gone through ten of those.
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post #4 of 8 (permalink) Old 02-16-2011, 04:18 PM
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This is the one I made and currently use. I got everything I needed from Lowe's, but had to adapt a few things because not all the parts he recommends can be found there or at Home Depot. The basic design works very well, though - 100% diffusion at several bps. I have a sales thread for a few of the fittings and some more explanation if you're interested. Oh, and if you're set on clear PVC, I believe some people have gotten it from

Good luck!
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post #5 of 8 (permalink) Old 02-17-2011, 03:56 PM
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If I was to do it again, I would make THIS one instead of the rex.
Not because Rex's reactor dont work good (It works great) but because I think this one looks better.
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post #6 of 8 (permalink) Old 03-08-2011, 03:30 AM
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I don't know if you are still interested but I made a cheap inline co2 reactor for my tank as I wasn't too keen on the green thing anymore either, it's based on the one made with the 2" tube but I wasn't keen on having to glue tubes together or running it into my canister filter(s).

I got myself a powerhead and decided to pump the water out of the tank, down 13mm tube until I had reached a height below the base of the tank, I then got a inline irrigation filter and filled it with bio balls, ran hose back up using elbows and looped back down to another bio ball filled filter then returned to the tank.

To put co2 into the line I got a cheap plastic non return valve and tore it in 2, keeping the male part which has a 13-10mm shoulder, cut the joining leg off a 13mm water tee and superglue the 2 pieces together which makes a real cheap Venturi.

I have a 70g and this all fits behind the tank with no worries and bubbling an average of 2bps I see almost no wasted co2 coming back into the tank.

It's a fairly cheap setup that's working for me so far
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post #7 of 8 (permalink) Old 03-08-2011, 03:34 AM
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It's really easy to make a griggs style reactor. I've never done any pvc plumbing and it was a snap. I highly recommend using a clear tube for the main piece!!

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post #8 of 8 (permalink) Old 03-08-2011, 01:39 PM
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i cheaped out on the amount of DIY i put into my co2 reactor... used something similar to this

used a normal plastic one:

with the correct bars, i think 3/4" thread with a 1/2" barb, straight ones, drilled the hole out where the red button is and pvc cemented a section of pvc pipe inside it (in place of the threaded tubing from the other thread) the only problem with the pipe is that i had to use a dremel to clear out some material so it would fit.

works like a champ, no bubbles from the outflow, heavy growth and a nice green drop checker on about a bubble/second.

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