Yugang CO2 Reactor - A Guide

[Yugang]

This thread is for the general discussion of the Article Yugang CO2 Reactor - A Guide. Please add to the discussion here.

 

[Mr.Shenanagins]

Thank you for this contribution @Yugang , We all absolutely appreciate it.

 

[Kwyet]

In Addendum B it says “it is important to set up the reactor in the tank”. It should say “below the tank” shouldn’t it?

 

[Noahspapa]

Is bypass used to “calibrate” the flow through the reactor?

 

[Naturescapes_Rocco]

It can be used (when set up properly) to dial in the flow through the reactor, yes!

 

[JayP]

Is bypass used to “calibrate” the flow through the reactor?

"Regulate" might be the better term. It just helps tame the flow through the reactor so its not rushing through too fast.

 

[Noahspapa]

I’ve been studying various threads and articles you all have put on the forum. Thank you for that!

In my next setup (36” x 20” x 20”) I intend to carbonate using a variation of the modular setup Rocco described. I just ordered the MDP-3500 pump, I have a netlea pre filter, and I could either build a DIY reactor with bypass or pull a small acrylic ARC reactor off a tank where it is currently overkill.

Do you think one approach is better than the other?

 

[Noahspapa]

I realize the pump has controllable flow rate and that could help, but with bypass I could use the pump to control the overall flow and the bypass to control the flow through the reactor.

 

[JayP]

I’ve been studying various threads and articles you all have put on the forum. Thank you for that!

In my next setup (36” x 20” x 20”) I intend to carbonate using a variation of the modular setup Rocco described. I just ordered the MDP-3500 pump, I have a netlea pre filter, and I could either build a DIY reactor with bypass or pull a small acrylic ARC reactor off a tank where it is currently overkill.

Do you think one approach is better than the other?

A couple things:
1. I'm using the MDP-3500 to run my Biomaster 850 on a 120cm tank right now that's cycling. That pump is way more than enough flow for that tank and I'll probably be running it at less than 50% once planted. I'm sure I could have gone with the MDP-2500, so for your smaller tank, you might consider that.
2. The ARC small reactor at full output capability on that same 120cm tank can provide more than a 1.5 ph drop (so even a much bigger potential drop with your tank). Since I don't want to have to bother with adjusting it, I'm leaving it set to that full potential, but running it in "regulator" mode rather than "overflow" mode. I feel comfortable doing this since I'm also using a DIY regulator with precision metering valve. If using an off-the-shelf regulator, it's important to keep close tabs on CO2 levels just as you would with an inline diffuser or other co2 diffusion method, since you don't have that overflow safety feature.

 

[Naturescapes_Rocco]

I’ve been studying various threads and articles you all have put on the forum. Thank you for that!

In my next setup (36” x 20” x 20”) I intend to carbonate using a variation of the modular setup Rocco described. I just ordered the MDP-3500 pump, I have a netlea pre filter, and I could either build a DIY reactor with bypass or pull a small acrylic ARC reactor off a tank where it is currently overkill.

Do you think one approach is better than the other?

In my main journals (Experiment/Many Lessons/Inert Sand Trials, see signature) I have never used a bypass with my reactors except in Inert Sand Trials. I plan to on this next build, but it's not required by any means! If you're limited on size/space, you can see if the fully-inline reactor build works, and if the flow is really rapid through the reactor, you could always add a bypass later.

See this post for different horizontal reactor orientation options

If you do decide on a bypass, note that not all of the reactor exits have to meet again with the main water flow! You can have it split, which also allows you to have two exits for water into your tank which can be really beneficial for flow pattern.

 

[Noahspapa]

Thank you. Yes - I saw the images you shared - I think with TRyan on this and will go through the above. Thanks again!

 

[Noahspapa]

A couple things:
1. I'm using the MDP-3500 to run my Biomaster 850 on a 120cm tank right now that's cycling. That pump is way more than enough flow for that tank and I'll probably be running it at less than 50% once planted. I'm sure I could have gone with the MDP-2500, so for your smaller tank, you might consider that.
2. The ARC small reactor at full output capability on that same 120cm tank can provide more than a 1.5 ph drop (so even a much bigger potential drop with your tank). Since I don't want to have to bother with adjusting it, I'm leaving it set to that full potential, but running it in "regulator" mode rather than "overflow" mode. I feel comfortable doing this since I'm also using a DIY regulator with precision metering valve. If using an off-the-shelf regulator, it's important to keep close tabs on CO2 levels just as you would with an inline diffuser or other co2 diffusion method, since you don't have that overflow safety feature.

Thank you. Ordered the 2500, will return the 3500.

 

[renesis]

Just adding this spreadsheet that helps calculate min/max power level for a given reactor length, diameter, port size/offset. Designed for my tank with the help of Claude, but could be useful for others. Double check results, as I haven't vetted all combinations, but it specced out well for my case. It made it easy to play with different scenarios.




Let me know if anything needs fixing, but just a little payback for all the knowledge learned from the valuable members here.

 

[Koan]

Reference for 90° stainless elbow fittings that match the ARC stainless Yugang reactor

Post in thread 'Annoyed at the default Aqua Rocks Colorado Acrylic Horizontal Reactor connectors?'

Jul 24, 2026

Thanks all. I reached out to ARC and sure glad I did. Here is the part for anyone else wanting to do this.

The threaded fitting piece is G1/2 threading. You can find the elbow fitting you need here: https://a.co/d/01PcvYD5

• Jeff Miotke

• 
• 
• 

Post in thread 'Annoyed at the default Aqua Rocks Colorado Acrylic Horizontal Reactor connectors?'

Aug 3, 2026

Well that simple elbow made all the difference in cleaning up this install.

• Jeff Miotke

• 
• 
• 

 

[Koan]

Reference for short direct fitting to replace stock long angled fitting on ARC acrylic Yugang reactor

Thread 'Annoyed at the default Aqua Rocks Colorado Acrylic Horizontal Reactor connectors?'

Jul 22, 2026

The existing connectors are seriously long, like 5-6" of added length, and at an angle that is either good or horrible for your setup.


If you want to just convert the reactor's connectors to standard 5/8" (aka 16/22mm aquarium tubing), all you need are these:



3/4" PVC Union Fittings, with a 3/4" female NPT thread.


Much better, WAY smaller! Easier to fit in my cabinet.

• Naturescapes_Rocco

• 
• 
• 

Post in thread 'Another Yugang post'

Apr 15, 2026

I'm still considering a bypass for my ARC small reactor but the trick on those is finding the best fittings to work with ARC's since they're not standard U.S. sizes other than the barbs themslves.

The couplings are 25mm (euro sizing) which you can get all 25mm PVC parts on amazon, OR you can get some 3/4" PVC Union couplings, which will actually fit the existing reactor sizes! I already did this previously and it worked great.

I used these, kept the original "screw ring" from the 25mm size. The flat half of the 3/4" union can sit just fine over the gasketed-side of the...

• Naturescapes_Rocco

• 
• 
•