Horizontal CO2 Reactor - Yugang 鱼缸 Reactor

[Uncle_R]

Thanks all, @Naturescapes_Rocco and others how long does it take to get your pH drop? It takes me [emoji[emoji[emoji[emoji6][emoji6]][emoji[emoji[emoji6]][emoji[emoji6]]]][emoji[emoji6][emoji6]][emoji[emoji[emoji6]][emoji[emoji6][emoji6]]]]hrs for a [emoji[emoji[emoji6]][emoji[emoji6][emoji6]]].[emoji[emoji[emoji[emoji6][emoji6]][emoji[emoji[emoji6]][emoji[emoji6]]]][emoji[emoji[emoji[emoji6][emoji6]][emoji[emoji[emoji6]][emoji[emoji6]]]][emoji[emoji6][emoji6]][emoji[emoji[emoji6]][emoji[emoji6][emoji6]]]][emoji[emoji6][emoji6]][emoji[emoji[emoji[emoji6][emoji6]][emoji[emoji[emoji6]][emoji[emoji6]]]][emoji[emoji6][emoji6]][emoji[emoji[emoji6]][emoji[emoji6][emoji6]]]]] drop. I’m surprised that it takes this long since my reactor is twice the calculated size.


Sent from my iPhone using Tapatalk Pro

@Art do you know why my replies sometimes do this from Tapatalk? Thanks

 

[Art]

Sorry, I don’t. I will try to see if there’s an update or a fix though.

 

[Naturescapes_Rocco]

@Naturescapes_Rocco and others how long does it take to get your pH drop?

Two things to mention (that you might already know, but could be helpful for others):

1. the 1.0 pH drop should always be measured from the "degassed baseline" to the measured in-tank final pH, not from the drop between when CO2 comes on to the time it turns off.

A Degassed Basline is a water sample removed from aquarium, left out for 24-48 hours and/or vigorously shaken with exposure to air, to get a fully CO2-free degassed baseline. We measure that, and compare that to the in-tank pH and check the difference. Very few (if basically no one) will get a 1.0pH drop from morning to evening in their tank, because plenty of CO2 will still be left in the water by morning to adjust the pH down.

2. What matters in these horizontal reactors is the surface area of the CO2 pocket in contact with the water. See my post here.
The largest surface area possible is when the reactor is filled to exactly 1/2 diameter. You will get a faster drop if you make sure the pocket is filled to the maximum level (but be careful, because this means that you'll also be injecting the maximum amount of CO2!).

My reactor is slightly oversized for my tank, (13:1 tank:reactor instead of the normal 17:1 size), so if I run it on maximum strength I will get a 1.0 pH drop (comparing degassed to in-tank water) in about 1-1.5 hours or less.
While this drop happens quickly, it injects way too much CO2 into my tank... about 45-50ppm CO2 tested with the pH drop method, a drop checker yellow, and a Hanna CO2 test kit (which I highly recommend).

So, I have to run my reactor at about 3/5 full, which reduces the pocket surface area and therefore reduces the strength. With even such a small difference in reactor pocket size, I go from 1 hour for a 1.0+ pH drop, to about 3 hours 1.0pH drop.

Not a problem! I just turn my CO2 on 3 hours before the lights come on, and turn it off about 1 hour after the lights go off.

 

[naseer]

Are you turning co2 off? I have noticed in mine that when the co2 is off the reactor fills almost completely woth water. Another issue could be not enough co2 injection to create a bubble.

I also noticed that the reactor fills with water as soon as the CO2 is turned off. Once the CO2 is running, the water level inside the reactor drops. I didn’t know this before.
Thank's.

I mean, if you're injecting CO2 there will be a pocket of gas. If there's no pocket, either the CO2 is getting absorbed SUPER fast, or you're not injecting (or you do have a gas leak somewhere).
These things are pretty simple in their design and should be easy to troubleshoot. What material is this btw, it looks good!

In the end, a gas pocket did form. I had to inject more CO2 to create more pressure in the reactor.
I used clear PVC to build the system.
Thanks!

The reactor fills with CO2 while on, half full of CO2. The reactor fills with water when CO2 is off because all the CO2, in the chamber, has dissolved into the water. This is 100% normal.

I didn’t know this before; for a moment, I thought I hadn’t built the reactor correctly.
Thanks!

 

[Pepere]

I dont suppose it matters any whether you have the horizontal reactor on the intake side or the output side…

 

[Kwyet]

I dont suppose it matters any whether you have the horizontal reactor on the intake side or the output side…

I think you need it on the output side so the overflow bubbles won’t get dissolved while working through your filter.

 

[Unexpected]

Output side.

 

[Bettatail]

I just start reading this thread, before I get into the calculated part of 魚缸 's design, a quick question -- what is the proper length if I use a 2" diameter PVC pipe as reactor on a 170G with 50G sump, the pump max flow rate is 4500L/1200G(around 3000L normal)

 

[Naturescapes_Rocco]

I just start reading this thread, before I get into the calculated part of 魚缸 's design, a quick question -- what is the proper length if I use a 2" diameter PVC pipe as reactor on a 170G with 50G sump, the pump max flow rate is 4500L/1200G(around 3000L normal)

Hey Bettatail, just responded to an ebay message from you lol!

What matters the most is the surface area of your tank (and sump), because CO2 gas can only escape and reach equilibrium through that open side of the aquarium. What are the dimensions of the tank in terms of depth and width? Height is not necessary, and flow rate isn't a big deal either.

The ratio recommended by Yugang is "17:1", aka "tank-surface-area : reactor-bubble-surface-area".

- If your tank was 200cm long by 55cm deep, the Surface Area that CO2 can be lost out of = 11,000cm2 aquarium.
- A standard 50 gallon tank (open air sump) is about 123cm long by 33cm deep, so SA = 4,059cm2 sump.
- Combine both to get 15,059cm2 total exposed surface that CO2 can escape.
- You want a reactor that has, at max power (50% filled, largest gas pocket surface area in a cylinder), 1/17th the surface area of your tank's surface area or better: 15,059/17 = 885cm2 reactor gas pocket max surface area. My overpowered reactor is more like 1:13, but 1:17 should be plenty.

Now that you know that, you can calculate the longest tube of PVC required at any diameter:
2" diameter pvc is about 5cm in diameter, so to calculate the length required is: 885cm2/5cm= 177cm, or about 70 inches, of 2" PVC length for maximum output.

Note that you can always increase the diameter of the pipe for increased power/shorter length (these reactors can be quite 'squat'!), and you can always build an oversized reactor and just run it 2/3 or even 1/4 full to prevent over-gassing your fish. Let me know if that all makes sense!

There is also a calculator spreadsheet here.

To summarize:

1. Tank Length x Depth = Tank Surface Area (TankSA). This is the only open area for CO2 to escape.
   
   
2. To get the minimum reactor internal surface area needed: TankSA/17 = ReactorSA
   
   
3. To get the length of any diameter tube needed: ReactorSA/TubeDia = Tube Length Needed

 

[SingAlongWithTsing]

I just start reading this thread, before I get into the calculated part of 魚缸 's design, a quick question -- what is the proper length if I use a 2" diameter PVC pipe as reactor on a 170G with 50G sump, the pump max flow rate is 4500L/1200G(around 3000L normal)

If your surface area is similar to mines

 

[Bettatail]

Thank you for the detail explanation, Rocco & Tsing,

and great design, Yugang!

 

[Art]

@Art do you know why my replies sometimes do this from Tapatalk? Thanks

I installed an update. Please let me know if that fixes it.

 

[Art]

Thank you for the detail explanation, Rocco & Tsing,

and great design, Yugang!

@Yugang

 

[Uncle_R]

I installed an update. Please let me know if that fixes it.

@Art I can't login to Scapcrunch through Tapatalk now. Maybe I should give up on it I really don't use it for anything else now.

 

[Yugang]

and great design, Yugang!

Thank you for your kind remarks.

I am really happy to see several hobbyists answering reactor questions and doing further tests. Unfortunately I will not have much time this year, but I do check ScapeCrunch from time to time. If really my contribution is asked for I may jump in, but the reactor and its know how are now rather common knowledge on ScapeCrunch.

My tank is doing well. Using overflow mode and around 20 ppm, really no need to look after it that much.

 

[Hawk984]

Best regards @Yugang

I would like to build such a reactor. The size of my aquarium is 105x40x50. If I did my calculations correctly, then with the ratio of 17, the reactor gas pocket max surface area is 247 cm2. I would be interested in what diameter of the reservoir I should make if the reactor body can be a maximum of 30cm long (without hose connections) because unfortunately I don't have a larger space in my furniture where I can place it. I guess I should also make a bypass branch for this size?! Thank you in advance for your answer.

 

[Yugang]

I would like to build such a reactor. The size of my aquarium is 105x40x50. If I did my calculations correctly, then with the ratio of 17, the reactor gas pocket max surface area is 247 cm2.

This looks correct, if you aim for a 1.5 pH drop from degassed water. For a 1.2 pH drop about half, 123 cm2, would be sufficient.

Starting from the 247 cm2, divided by 30 cm length, you would need a tube diameter of about 8 cm.

I guess I should also make a bypass branch for this size?!

A bypass is nice, because with a slow water flow in the reactor there is less risk for noise, but for most cases it is not essential. I believe most hobbyists don't care about using a bypass. For the functionality of the reactor, absorption of CO2, almost every flow of water works, as long as the water is not stagnant.

 

[Hawk984]

Thanks for your quick reply @Yugang

I have another question, can I control the pH drop in this reactor? I think this can only be done if the height of the water inlet and outlet is adjustable, i.e. the water surface can be reduced or increased? In general, how many bubbles/second does CO2 need to be dissolved?
Thanks again for your reply.

 

[Yugang]

I have another question, can I control the pH drop in this reactor?

Yes, as described earlier in this thread, there are three different ways to operate the reactor:
-1- Overflow mode, as I use it. In overflow mode the reactor purges itself, as discribed earlier in the threads on horizontal reactor and CO2 Spray Bar. This purging will continuously push a little gas out from the reactor, and hence keep it perfectly pure CO2. By the end of the day the pure CO will dissolve, and (nearly) no gas will be left in the reactor.
-2- Inject with a precision CO2 regulator / CO2 needle valve. No CO2 can get 'lost', so ultimately all CO2 that comes from the regulator must get absorbed in the water. If there would be too much other gas (non CO2) in the reactor, the reactor CO2 absorption efficiency will go down, then the reactor will purge itself, until it reaches the state that all CO2 flow from the regulator will be absorbed in the water. So also here no problem.
-3- Inject with a pH/CO2 controller. Very similar to to argumentation -2-. No problem, the controller will guarantee that we reach target CO2 and stability, irrespective of the reactor purging itself in the process.

Post in thread 'Horizontal CO2 Reactor - Yugang 鱼缸 Reactor'

Sep 9, 2023

This post is to summarise my understanding of the physics in the reactor, how to explain a remaining gas pocket after CO2 has been turned of, but arguably this post is less relevant for most users.

I recently had some PM exchange with a friend who observes an unexplained gas pocket in the reactor, that at least partially remains after the CO2 has been turned off at night. I usually don't observe that in my reactor (but it can sometimes happen) and I believe I now understand what is going on when it happens

The short story is - don't worry, unless too little CO2 is...

• Yugang

• 

In general, how many bubbles/second does CO2 need to be dissolved?

Various bubble counters have different bubble sizes, so it is hard to give an answer here.

 

[Unexpected]

Best regards @Yugang

I would like to build such a reactor. The size of my aquarium is 105x40x50. If I did my calculations correctly, then with the ratio of 17, the reactor gas pocket max surface area is 247 cm2. I would be interested in what diameter of the reservoir I should make if the reactor body can be a maximum of 30cm long (without hose connections) because unfortunately I don't have a larger space in my furniture where I can place it. I guess I should also make a bypass branch for this size?! Thank you in advance for your answer.

If horizontal space is an issue, you can simply divide the length in half and use 2 pipes (totaling the needed length) in parallel. I've done this and it works the same. I used some 90 degree angle barbs and used some leftover tubing.