Horizontal CO2 Reactor - Yugang 鱼缸 Reactor

[hamfist]

Oh wow yeah I recognize yours from earlier in this thread, I always thought it looked pretty badass!

That is such an incredibly over-generous description.

 

[TRyan]

Baby powder and a rubber mallet .... that's a great idea. I wish I knew that sooner.

I recently completed an upgraded version of my reactor. When I built my first one, I didn't use any unions or tubing so it is impossible to clean it.

Here's the new and improved version for my 90p tank.

 

[N72826]

Just an update for those interested


I am going to borrow a dremel/rubber mallet from my dad soon. I just thought I would (very loosely) dry fit it to get an idea of what I'm working with here. And man, I had no idea how big this was going to be for some reason haha. Once I use the dremel to sand down the lip in the socket of the reducer couplings, I will have a more accurate idea of how it's going to look/any changes I need to make. I'm really liking this even though I have no idea where it's going to be mounted because my "inside cabinet" idea is now out the window

I'm definitely going to consider adding more points that will allow me to clean it out before I cement everything in place.

Also, I just realized I hadn't shared a picture of the tank this is going on, so that is attached as well.

 

[N72826]

So everything fits now that I’ve sanded the sockets a bit. I just wanted to check with you knowledgeable folks before I cement, because now I’m realizing something.

Based on my understanding, the inlet side elbow orientation should be aimed downward to avoid splashing, and the outlet side elbow orientation is the one that determines the “power” of the reactor.

Photo from the yugang guide:



Given that, what should the "starting position" be of the outlet side, in other words, how should the outlet side be cemented in place? I have it at what I believe to be maximum power according to the guide in the photos below, and wanted to ask you guys if that's where I should cement it.

I’m going to use braided vinyl tubing to attach the stubs that poke out of either end of the reactor to the rest of the setup so that it will be capable of rotation, but I just wanted to get an idea of how it’s going to work.

Here are a couple of photos of how it looks dry-fitted:

 

[Naturescapes_Rocco]

So everything fits now that I’ve sanded the sockets a bit. I just wanted to check with you knowledgeable folks before I cement, because now I’m realizing something.

Based on my understanding, the inlet side elbow orientation should be aimed downward to avoid splashing, and the outlet side elbow orientation is the one that determines the “power” of the reactor.

Correct, the height of the offset outlet determines the max bubble size (because any larger bubble than that causes the gasses to exit the reactor, instead of being dissolved into the water).

If you cement everything in place, you won't be able to adjust your reactor's power.

Instead, I'd recommend trying to fit some PVC Union Couplings on both sides of your reactor, which will still allow you to not only rotate the reactor while all parts are still cemented, but also allow you to dissasemble it for cleaning.

See @TRyan's reactor:

If he included a 3rd Union Coupling where the arrow indicates, his reactor could be removable and rotatable. He doesn't need that, because his reactor has a fixed outlet height, so it wouldn't improve anything to be able to rotate. Instead, his PVC Union Couplings allow him to disassemble the reactor and clean it all if necessary.

 

[N72826]

If you cement everything in place, you won't be able to adjust your reactor's power.

Instead, I'd recommend trying to fit some PVC Union Couplings on both sides of your reactor, which will still allow you to not only rotate the reactor while all parts are still cemented, but also allow you to dissasemble it for cleaning.

Well, I had already planned on enabling myself to rotate the reactor, but I am planning on doing it the way I saw Yugang did it (braided vinyl hosing in the photo below). Though I can admit that those union couplings are much sexier and I would consider putting them on either side if I hadn't already bought the hosing and clamps.

I guess my question might be a little silly, but even in the example you have provided of @TRyan's reactor, he still had to cement elbows within each side (unless he didn't and I'm tripping). My question was more so, does the initial position that you cement the outlet elbow in matter? I plan on giving myself the ability to rotate the reactor regardless.

Sorry if I was a little confusing, and thank you so much for your advice.

 

[xNitroPT]

Well, I had already planned on enabling myself to rotate the reactor, but I am planning on doing it the way I saw Yugang did it (braided vinyl hosing in the photo below). Though I can admit that those union couplings are much sexier and I would consider putting them on either side if I hadn't already bought the hosing and clamps.

I guess my question might be a little silly, but even in the example you have provided of @TRyan's reactor, he still had to cement elbows within each side (unless he didn't and I'm tripping). My question was more so, does the initial position that you cement the outlet elbow in matter? I plan on giving myself the ability to rotate the reactor regardless.

Sorry if I was a little confusing, and thank you so much for your advice.

If I’m understanding you, you will use the clamp and braided hose to rotate (loosen clamp, rotate reactor, then retighten clamps). Your outlet won’t matter if it’s glued, but your inlet will. If everything is glued in place and you rotate the reactor piece - yes the outlet can be controlled but the inlet rotates with it. ie) You might be trying to decrease the power by rotating outlet upwards, but that will change the way the inlet below points too. Water may be noisy with that since elbow inlet purpose is to always aim down. So you’re right about questioning that.

Personally, I don’t have an elbow on my inlet. If you have a bypass, you can control the flow already and it’s silent in my experience - when you set it to low flow that is. (Slower flow is better anyways) Others can chime in on the elbow.

Ignore all this if you don’t plan on cementing your elbows in… but then I’m not sure how you’d even access them if you’re gluing the rest of the pieces…

 

[N72826]

If I’m understanding you, you will use the clamp and braided hose to rotate (loosen clamp, rotate reactor, then retighten clamps). Your outlet won’t matter if it’s glued, but your inlet will. If everything is glued in place and you rotate the reactor piece - yes the outlet can be controlled but the inlet rotates with it. ie) You might be trying to decrease the power by rotating outlet upwards, but that will change the way the inlet below points too. Water may be noisy with that since elbow inlet purpose is to always aim down. So you’re right about questioning that.

Yes, that’s exactly how I plan on rotating the reactor to adjust the power, and that’s exactly why I am concerned about rotating it after cementing both an inlet and outlet elbow in a static position—because the inlet would also be rotated thus potentially creating a noise problem.

I’m glad I’m not completely insane lmao.

Personally, I don’t have an elbow on my inlet. If you have a bypass, you can control the flow already and it’s silent in my experience - when you set it to low flow that is. (Slower flow is better anyways) Others can chime in on the elbow.

Awesome. You have essentially put all my concerns to rest with this suggestion.

Now I wish I hadn’t sanded the other reducer coupling but I believe I should still be able to use it just fine.

Ignore all this if you don’t plan on cementing your elbows in… but then I’m not sure how you’d even access them if you’re gluing the rest of the pieces…

I’m 100% set on cementing the outlet elbow, I don’t know how else this build would be accomplished.

Following your suggestion, I probably won’t include an inlet elbow though for the sake of simplicity.

The only things not being cemented are those braded vinyl pieces on each side that will allow me to rotate the reactor, as well as any other areas of braided vinyl I might add into the circuit that would allow me to clean it easier. I’m not decided on that yet because it’s already way bigger than I thought.

Thank you so much for your input, nitro.

 

[sootshe]

Hi all,
Newbie here & trying to get my head around this reactor.
I've read through nearly all of this thread & have a few questions.

Is this reactor just a cylindrical tube with an inlet & an outlet & a port to inject CO2?

I've seen quite a few photos & diagrams that show the main tube with other tubes inside the main tube that have slots &/or holes & that whole tube contained within another plastic chamber.

Also, instead of connecting this reactor to an external power filter can you just position it in the bottom of the tank & connect a small powerhead to the inlet??

 

[Yugang]

Newbie here & trying to get my head around this reactor.

For a good summary, you may prefer this article

Article 'Yugang CO2 Reactor - A Guide'

Contents: Benefits of Yugang reactor Calculate the reactor dimensions Overflow mode, regulator mode, pH/CO2 controller Overflow mode, step by step instruction Regulator mode, pH/CO2 controller mode, step by...

• Yugang
• Sep 15, 2025
• 20 min read
• Reaction score: 12
• Comments: 11
• Category: CO2 in the Planted Aquarium

The more complicated pictures, the box with the internal bypass is a more experimental phase and you may want to ignore these as beginner. Recommend to use the simple external bypass as described in above article.

Using a separate pump for the reactor is possible, but as the reactor gives very little reduction of the flow you may prefer to just use the filter to power it.

 

[sootshe]

Thanks for your reply,
I had read that article, but still confused.

If you connect that reactor to the outlet of a canister filter, aren't you pushing 1,000 or 2,000 or 3,000 litres per hour through the reactor anyway? (depending on the the output flow of the canister filter). I understand that you would use the flow control valve to adjust the flow, but I can do that with an inline powerhead as well. I was thinking of using a 300LPH powerhead connected a short distance from the inlet of the reactor tube.

Currently I'm using the attached version of an in tank diffuser but I can't get enough output of CO2 into the tank.

 

[Yugang]

If you connect that reactor to the outlet of a canister filter, aren't you pushing 1,000 or 2,000 or 3,000 litres per hour through the reactor anyway? (depending on the the output flow of the canister filter). I understand that you would use the flow control valve to adjust the flow, but I can do that with an inline powerhead as well. I was thinking of using a 300LPH powerhead connected a short distance from the inlet of the reactor tube.

The reactor will work under various water flows, almost independent of flow, as long as the water is not stagnant. So you may use filter output, powerhead, it will all work. I believe most users do not really need a bypass to adjust flow, but I would say it is a nice to have.

I prefer to have a nice gentle flow in the reactor, with just small ripples so that I can see the water is not stagnant. Therefore I lead most of my filter flow through a bypass, and only a small portion through my reactor.
Two reasons for this:

• we don't want too high flow with potentially some water splashing and starting to make noise in the reactor
• When the flow is gentle, small ripples, it will be easier to optimise the "overflow" mode, as compared to more waves inside that could give more irregular and larger CO2 bubbles to escape.

But again, these are arguably subtleties, and most owners probably don't care.

I hope this was helpful and makes it less confusing.

 

[sootshe]

Thanks for the input.

I'm going to build one & will let you know how it goes. Getting it to sit horizontal in the tank is going to be a challenge.

Thanks again.

 

[Naturescapes_Rocco]

Just an FYI sootshe, these reactors sit outside of the tank Usually underneath, in your canister/inline pump line system.

 

[sootshe]

So, my experiment didn't work out & I would like to build one of these reactors & connect it in line with my return pump.
So am I correct in the following?:
1. The reactor is just a plain tube with an inlet & outlet for the water & an inlet for the CO2?
2. The water flow is supposed to be just a gentle flow? I don't understand this - isn't the water flow the same as the output of the pump?
3. When connected into the system, won't the cylinder just fill up completely with water? ....or does the pressure of the CO2 push the water level in the cylinder down?
4. You say that most people don't use the bypass. So then, how can you ensure that there is only a gentle flow through the reactor?

 

[JayP]

1. The reactor is just a plain tube with an inlet & outlet for the water & an inlet for the CO2?

Essentially, yes.

2. The water flow is supposed to be just a gentle flow? I don't understand this - isn't the water flow the same as the output of the pump?

Not if you add a bypass.

3. ....or does the pressure of the CO2 push the water level in the cylinder down?

Yes.

4. You say that most people don't use the bypass. So then, how can you ensure that there is only a gentle flow through the reactor?

Perhaps most people don't, but they probably should. I put a bypass on my third reactor and wish I'd done it on my other two.

 

[sootshe]

Thanks so much for clarifying.

 

[Mr.Shenanagins]

So, my experiment didn't work out & I would like to build one of these reactors & connect it in line with my return pump. If this is a sump setup, I highly recommend putting the reactor on its own loop with a separate smaller pump. It is much easier to dial in flow, without affecting your return. You can also just leave the return for the reactor in the sump near the main return.
So am I correct in the following?:
1. The reactor is just a plain tube with an inlet & outlet for the water & an inlet for the CO2? Yes and no, did you calculate the measurements for your tube size required for your tank?
2. The water flow is supposed to be just a gentle flow? I don't understand this - isn't the water flow the same as the output of the pump? No, you don’t want the full power of your return pump to run this reactor. This is why people use a bypass to throttle down the amount of flow through the reactor.
3. When connected into the system, won't the cylinder just fill up completely with water? ....or does the pressure of the CO2 push the water level in the cylinder down?

It can and will yes, but the co2 will displace it until it reaches the output and will burp when the co2 overflows.

4. You say that most people don't use the bypass. So then, how can you ensure that there is only a gentle flow through the reactor?

I have return pumps too, but I use a separate 100gph pump for my 10x6” reactor with 5/8” hose inlet/outlets. Works great, no noise and plenty of CO2

 

[sootshe]

"If this is a sump setup, I highly recommend putting the reactor on its own loop with a separate smaller pump. It is much easier to dial in flow, without affecting your return. You can also just leave the return for the reactor in the sump near the main return."

Yes, I have a 50 G tank with a 30 G sump, running a fluidized bed. I can never get enough CO2 into the tank & I'm thinking that the turbulence of the fluidized bed is expelling all the CO2. I run wavemakers in the sump & position two of them to create surface turbulence to oxygenate the water. I've tried adjusting them to create less surface agitation, but still not enough CO2 from diffusers to turn the drop checker green. Drop checker is always dark blue even if I leave the CO2 on for 24 hours.

Yes and no, did you calculate the measurements for your tube size required for your tank?
No, I haven't done that yet as I'm not sure how to calculate that taking the sump into consideration. My tank is 48" long x 18" wide & the sump is 36" long x 12" wide.

I have return pumps too, but I use a separate 100gph pump for my 10x6” reactor with 5/8” hose inlet/outlets. Works great, no noise and plenty of CO2
That sounds like a great way to go & I'd much prefer to not interfere with my main pump system. How did you come up with the sizing of the reactor pump?

 

[Mr.Shenanagins]

Ahh I see. Yes you have an uphill battle with that sump for sure. In all honesty though, that is an overkill setup for a planted tank. Not taking away from your hard work and desire to have as much filtration power as possible though.

Your calculations will include both surface area of your tank and the sump added together.

The reactor pump was just a spare pump I happened to have on hand. You literally need something with enough power to run water through the reactor, that’s it. Too much splashing will allow co2 escape unnecessarily and make the reactor noisy.