Horizontal CO2 Reactor - Yugang 鱼缸 Reactor

[dantaylornz]

I am contemplating building a horizontal reactor - I have found the information provided by @Yugang very helpful and quite compelling - much appreciated.

I haven't yet started getting too far into the details of working out how to size one for my 120x45x50cm tank - I have a couple of questions which I'd be grateful for some feedback on first if possible:

1) I run an Oase Biomaster Thermo 850 on my tank - many people will know these filters have a reputation for building up and then releasing quite a bit of trapped air from time to time. One of the issues I have with my current vertical reactor is that this air builds up at the top and then makes the reactor noisy with water splashing which is annoying. I have wondered about much of a problem this will be for a horizontal reactor in terms of impacting its efficiency and how I can avoid it. I have contemplated running a bypass pipe parallel to and above the level of the reactor so that trapped air rises and travels around the reactor but I'm probably overthinking this and I'm guessing it may not work due to the flow anyway. Any comments or suggestions on air passing through the system and how much of a problem this really is?

2) I see a few people suggesting that a transparent reactor is unnecessary (ARC thread) in which case it would be even easier for me to knock one of these together using readily available PVC plumbing fittings. Transparent pipe that works with standard fittings may be harder to get hold of where I am. I think that the main reason transparency has some appeal to me is being able to verify how quickly the CO2 is building up inside the reactor in order to adjust my regulator to minimise reduce CO2 wastage. Is this valid - are the people using opaque designs potentially wasting more CO2 to overflow or are they monitoring/controlling this in another way I'm not thinking of?

3) My water is quite hard (approx. 8 pH out of the tap) so this does affect CO2 absorption a bit. I tend to drive between 1.2 - 1.5ph drop with my current setup but I do think my CO2 usage will be a bit higher than others. One of the outcomes I'm hoping for is a bit more efficiency out of this reactor type where I waste less CO2 (fewer bottle fills). Do I need to allow for a bigger reactor to maximise surface area to make sure of this or does this take care of itself?

4) I do have a pH controller. I assume this doesn't really work well with the horizontal design because of the need to build up a gas bubble in the top of the reactor making the effect of the CO2 control quite laggy?

 

[Pepere]

I run an Oase Biomaster Thermo 850 on my tank - many people will know these filters have a reputation for building up and then releasing quite a bit of trapped air from time to time

I am using an Oase Biomaster 350 on my DIY horizontal reactor. Intake is through a glass lily pipe with a surface skimmer I had 1 incident where the Biomaster was sucking air down the lily pipe and then purging it. This caused gas overflow out the spray bar leading me to think I had the co2 flowing too much for a while before I noticed the real problem…I had my flow turned down to 1 bubble a second and the overflow was not reducing.

Essentially plant matter had gotten stuck on the Lily pipes instake grill at the bottom causing increased flow from the surface skimmer causing it to pull in air. I solved this by fitting a coarse intake sponge over the bottom of the lily intake strainer. Hasnt recurred since then.

If you are getting air in the canister it is getting in there somehow, and you just need to track down how.

I have contemplated running a bypass pipe parallel to and above the level of the reactor so that trapped air rises and travels around the reactor but I'm probably overthinking this and I'm guessing it may not work due to the flow anyway

Its not likely to work as intended.. tracking down your air source in the filter is a better plan.

I see a few people suggesting that a transparent reactor is unnecessary

I worried about this as well. I use an Oase spray bar for my outlet under the waterline across the back aimed up slightly for water surface disturbance. When the co2 injection rate exceeds absorption, gas bubbles get discharged from the spray bar and are noticeable. You simply adjust flow rate down slightly and wait 10 minutes or so to guage result. I have heard suggestion to adjust until overflow bubbles happen every 50 tp 60 seconds for maximum output with minimum wastage. A transparent reactor wouldnt make the adjustment confirmation any faster in my opinion…. My reactor gives me a maximum ph drop of 1.4 when I get bypass bubbles. I have it turned down a bit below that so that I dont get noticeable bypass bubbles and my ph drop is around 1.2 at equilibrium.

Do I need to allow for a bigger reactor to maximise surface area to make sure of this

Conceivably, but @Yugang might be better able to assist with that.

do have a pH controller. I assume this doesn't really work well with the horizontal design because of the need to build up a gas bubble in the top of the reactor making the effect of the CO2 control quite laggy?

I would think it would work fine. Whether one is building a gas bubble in the reactor or just raising co2 levels in the tank, the system is simply waiting for ph level to drop before shutting off the soenoid to cut off gas flow. You still have a metering deviceto meter gas flow rate into the reactor. For myself I use the reactor size as my failsafe to prevent gassing the fish. A PH controller would provide this backstop allowing a larger reactor size which conceivably would allow co2 levels to get to target faster…. I tend to prefer not relying on a ph controller in case of callibration issues myself, but I dont have experience using them and hence dont have a confidence level one way or the other…

 

[Unexpected]

When I speak of efficiency with a Yugang reactor , I'm speaking about the lower energy required to run the system. All you need is a gentle flow through the reactor. Having a bypass can help you achieve this flow especially with a big filter like yours. That said, you may get more out of the tank because the reactor is so consistent. If your needle valve is on the higher end, you won't need to make changes after overflow mode is set.

Regarding the filter purging air, I would say you would have a small decrease since the gas chamber would be a mix of air and CO2. Overflow mode helps here too, the purge from overflow mode allows the chamber to remain almost all CO2. However, if the filter is purging air faster than overflow mode purges, this may cause a decrease.

ARCs option is very nice, with the adjustability, you could potentially adjust to compensate for the filter purge. Or could build one slightly oversized. I'd be prepared to build 2 just for testing. Build one at the correct size and see how it performs with your filter purge. Go bigger if you need to.

 

[Pepere]

Having a bypass can help you achieve this flow especially with a big filter like yours.

If you do opt fir a bypass, make sure your co2 injection comes after the bypass.


A concern I would have with the bypass would be, not knowing if the overflow bubbles were from co2 gas or atmospheric air purging from the pump.. one could of course use hydronic heating fittings that purge air from a system, such as building a pvc chamber that allows air bubbles to rise to the surface of a larger chamber with a float valve at the top to purge air.




But before going to such efforts I would investigate how air is getting into the canister. Eliminating that is easier and cheaper than removing it before the co2 reactor.

 

[Naturescapes_Rocco]

1) I run an Oase Biomaster Thermo 850 on my tank - many people will know these filters have a reputation for building up and then releasing quite a bit of trapped air from time to time.

I'm a biomaster "master" and have used the filters for years now. This is an issue with cavitation, where the pump is pushing more water than can move through the filter. The 'new' Biomaster v2 series has fixed this issue. They only changed two parts on the filters, and you can do it yourself:
1) Either buy the new prefilter pipe or just drill the holes in your old one much much larger. Almost as big as you can get them without breaking the prefilter pipe itself.
2) Buy the upgraded underplate. This is a non-negotiable if you want to eliminate purging. It fits all biomaster heads and is the #1 thing that will eliminate purging. My filters haven't purged air for over a year because of these upgrades, and I've literally tested it on every possible combination of filters, parts, sizes, etc. from Oase.

One of the issues I have with my current vertical reactor is that this air builds up at the top and then makes the reactor noisy with water splashing which is annoying. I have wondered about much of a problem this will be for a horizontal reactor in terms of impacting its efficiency and how I can avoid it.

I address this in my thread Testing the Aqua Rocks Colorado Acrylic Horizontal CO2 Reactor on a large tank. There is basically no noise at all with a horizontal reactor, that's one of the main benefits. Even when mine is >50% full, it's a silent trickle at most, or literally silent 90% of the time.

I have contemplated running a bypass pipe parallel to and above the level of the reactor so that trapped air rises and travels around the reactor but I'm probably overthinking this and I'm guessing it may not work due to the flow anyway. Any comments or suggestions on air passing through the system and how much of a problem this really is?

I really don't think it's a problem. If you have it mounted in a way that you can physically tilt one side up, you can simply manually manouvre it until the air has been sucked up into your tank if necessary, but the design of these reactors doesn't require a bypass of any kind, because they're more efficient with a large pocket of gas.

2) I see a few people suggesting that a transparent reactor is unnecessary (ARC thread) in which case it would be even easier for me to knock one of these together using readily available PVC plumbing fittings. Transparent pipe that works with standard fittings may be harder to get hold of where I am. I think that the main reason transparency has some appeal to me is being able to verify how quickly the CO2 is building up inside the reactor in order to adjust my regulator to minimise reduce CO2 wastage. Is this valid - are the people using opaque designs potentially wasting more CO2 to overflow or are they monitoring/controlling this in another way I'm not thinking of?

Ok I'm glad you saw the thread! One of the issues I'm having is that when my temps are cold and my surface agitation is majorly oxygenating the water, I think I'm getting a pocket of air as well as CO2 in my reactor, which hurt my efficiency. More testing is needed, but being able to see it has been imperative to my success with it. I know others might disagree, and I know opaque parts are cheaper, but I genuinely think I will never not use a transparent reactor (as mentioned in my thread). I think it's one of those "many won't know until they try" sort of things. But, would you use a sump that's completely opaque? What about a drop checker that's hard to read? I believe it really has helped me understand, practice, and dial in my reactor to have it clear.

Do I need to allow for a bigger reactor to maximise surface area to make sure of this or does this take care of itself?

Just make sure your reactor has a maximum (50% full) pocket of 1/15th or larger of your tank's surface area, and you'll be good. 1/17th is what Yugang recommends, but after my experience of my reactor at 1/13th the size of my tank, I'm glad I have a larger reactor to utilize (I run a LOT of surface agitation for oxygen so I use more CO2 because I also lose more CO2 to offgassing).

Your tank is 120x45cm, so 5400cm2 surface area allows CO2 to escape. at 1/15th power, ryu would need a reactor that is 360cm2 max surface area.
If you use 4" PVC (about 10cm in diameter), you would need a pipe/reactor length of ~36cm (10cmx36cm=360cm2). Your 4" PVC reactor would be about 36cm long. If you want to make it more powerful, almost overkill, either make the tube diameter larger, or make the length longer (or both).

4) I do have a pH controller. I assume this doesn't really work well with the horizontal design because of the need to build up a gas bubble in the top of the reactor making the effect of the CO2 control quite laggy?

I think you assume wrong! If you see my ARC thread, you can see my pH meter taking readings during injection. It actually reacts just as quickly as any other reactor, and only a little slower than with in-tank or in-line diffusers. If I have it come on at 5am, it starts dropping the pH already at 5:02am. If it shuts off at 2pm, by 2:30 the pH has already risen by 40% to baseline.

I think it would be a great option for you! Get your filter fixed/upgraded and it'll never purge again.

 

[dantaylornz]

Thanks for all the feedback so far - much appreciated. I don't have a lot of time for experimentation these days so I'm trying to settle on a design before I build something hoping to nail it in one go. A few responses on the Oase Biomaster air purging issue first of all:

I am using an Oase Biomaster 350 on my DIY horizontal reactor. Intake is through a glass lily pipe with a surface skimmer I had 1 incident where the Biomaster was sucking air down the lily pipe and then purging it. This caused gas overflow out the spray bar leading me to think I had the co2 flowing too much for a while before I noticed the real problem…I had my flow turned down to 1 bubble a second and the overflow was not reducing.

Essentially plant matter had gotten stuck on the Lily pipes instake grill at the bottom causing increased flow from the surface skimmer causing it to pull in air. I solved this by fitting a coarse intake sponge over the bottom of the lily intake strainer. Hasnt recurred since then.

If you are getting air in the canister it is getting in there somehow, and you just need to track down how.

Its not likely to work as intended.. tracking down your air source in the filter is a better plan.

I've already been through an extensive process of trying to track down air leaks ever since owning this filter (about 3 years). Initially it was annoying but didn't create any major problems as I used to use an inline CO2 diffuser and only changed to a reactor 18 months ago. I don't run lily pipes at all or anything else that could introduce air (I use a separate Eheim skimmer). I've added clamps to fittings, tried to lubricate seals on the filter, drilled a many additional holes in prefilter pipe as I could etc. etc. Based on information from various forums this definitely seems to be more of an issue with the 600 and 850 size filters with larger pumps and more flow.

I'm a biomaster "master" and have used the filters for years now. This is an issue with cavitation, where the pump is pushing more water than can move through the filter. The 'new' Biomaster v2 series has fixed this issue. They only changed two parts on the filters, and you can do it yourself:
1) Either buy the new prefilter pipe or just drill the holes in your old one much much larger. Almost as big as you can get them without breaking the prefilter pipe itself.
2) Buy the upgraded underplate. This is a non-negotiable if you want to eliminate purging. It fits all biomaster heads and is the #1 thing that will eliminate purging. My filters haven't purged air for over a year because of these upgrades, and I've literally tested it on every possible combination of filters, parts, sizes, etc. from Oase.

I address this in my thread Testing the Aqua Rocks Colorado Acrylic Horizontal CO2 Reactor on a large tank. There is basically no noise at all with a horizontal reactor, that's one of the main benefits. Even when mine is >50% full, it's a silent trickle at most, or literally silent 90% of the time.

...

I think it would be a great option for you! Get your filter fixed/upgraded and it'll never purge again.

From my research and attempts to solve this I think you are right about this the root cause of the air purging issue. I've already doubled the number of holes in my prefilter pipe previously so I think I've probably perforated that as much as I can. I've been looking to see how I can get hold of the V2 underplate - I'm in NZ so just trying to find a supplier who will ship that to me at a reasonable price which I've not been able to do so far, but I plan to get it. I've seen conflicting information on whether the impeller design has been changed as well? Perhaps @Naturescapes_Rocco you could comment on that? My only comment on upgrading the filter is that the upgraded underplate will reduce air buildup and prevent large purges and just allow the air to escape in small doses without building up so I've still been concerned about this ending up in the reactor - even in smaller doses. I will get the newer inlet pipe if I can and the Oase prefilter pipe when I can just in case that makes more of a difference than I have been able to with my DIY approach.

Onto the Yugang reactor comments:

When I speak of efficiency with a Yugang reactor , I'm speaking about the lower energy required to run the system. All you need is a gentle flow through the reactor. Having a bypass can help you achieve this flow especially with a big filter like yours. That said, you may get more out of the tank because the reactor is so consistent. If your needle valve is on the higher end, you won't need to make changes after overflow mode is set.

Regarding the filter purging air, I would say you would have a small decrease since the gas chamber would be a mix of air and CO2. Overflow mode helps here too, the purge from overflow mode allows the chamber to remain almost all CO2. However, if the filter is purging air faster than overflow mode purges, this may cause a decrease.

ARCs option is very nice, with the adjustability, you could potentially adjust to compensate for the filter purge. Or could build one slightly oversized. I'd be prepared to build 2 just for testing. Build one at the correct size and see how it performs with your filter purge. Go bigger if you need to.

At the moment one of my goals from building a Yugang reactor as stated previously would be to improve CO2 injection efficiency and be able to swap my bottle every 3 months, for example, rather than every 2. My needle valve (CO2 Art Pro-Elite regulator) is quite wide open at the moment and I'm pretty sure I could improve dissolution with more surface area in contact with the water flowing through.

To that end, I am contemplating whether there are actually better advantages with the rectangular box style which @Yugang has shown in previous posts vs the ARC style round tube. My theory being that it is possible to achieve a large contact area between gas and water in this configuration without having to build up as much of a gas pocket first after the solenoid switches on. Whereas the tube style potentially needs a gas bubble large enough to get to 50% of the tube to maximise the full diameter of the pipe. Does anyone have any comments on this - am I overthinking it? I'm thinking if I went this way, I'd be more likely to implement a bypass to avoid disrupting the flow from my pump (want to keep flow in the tank as high as possible) and just have a gentler flow passing through the rectangular reactor. The round pipe style looks a bit easier to build to me.

Thoughts/comments anyone?

 

[Max Power]

I want to thank @Unexpected for introducing me to this new forum, but most importantly for him being the first ever to build the Horizontal CO2 Reactor. I feel honored that "Yugang Reactor " as he calls it (Yugang 鱼缸 means fish tank) is introduced in @Unexpected journal, but it would be a pity if that journal gets cluttered with too much reactor talk. So let me open a dedicated thread for discussions, questions and help on this Horizontal Reactor.

I have been experimenting for years with CO2, and at some time I took videos of my (modified) Aquamedic reactor to watch the bubbles in slow motion. To my surprise I found that the combined surface area of the bubbles was not very high for achieving a 1.5 pH drop in my 250 liter tank, and that CO2 absorbs so fast in water that the lifetime of bubbles is quite short. So .... we don't need to juggle bubbles at all, we can just create a very simple absorption interface between flowing water and a pocket of CO2 above it. The Horizontal reactor is surprisingly simple, and has some benefits that we won't find in diffusers or conventional Cerges / Griggs bubble reactors:

• Simple rules to find the correct dimensions for any tank, a small nano tank or a huge tank the size of a swimming pool.
• Very easy and cheap to build with plumbing materials. No fragile parts, low risk of leakage or malfunction.
• 100% CO2 absorption efficiency
• No need to experiment with vortices, venturis, diffusers, needles wheels, impellers / rotors, multi stage reactors - it is just a pipe with a gentle flow of water.
• No noise
• No mist in the tank
• No maintenance, and stable performance over time
• Virtually no reduction of flow from pump
• A purging valve is optional, as the reactor will purge itself from excessive trapped air.
• The reactor can be configured so that in the event of a failure, CO2 injection will not exceed a limit and fish cannot be gassed. Inherently safe.
• The reactor can be configured so that we do not need a precision regulator, because the reactor controls the CO2 injection rate

View attachment 2030

Or a multi stage version ...
View attachment 2031

A detailed thread can be found on UKAPS, linked with the kind permission from Scapecrunch forum moderators #1

I am happy to help new users to verify the calculations on reactor dimensions for their tank, please send me a PM.

There are a few things that needs to be looked at with regards to this design from what I can see, but as I have no experience using this type of CO2 injection I might be wrong.

1. The main problem with this type of reactor would possibly be a buildup of a surface film during the injection phase. If people are using surface skimmers or for that matter have a high degree of surface agitation they might not notice that they have a problem in the aquarium. I suggest reading the link below for a brief overview of the problem that would be caused by this: https://www.researchgate.net/publication/228589709_Air-Water_Gas_Exchange , section 2.5 is the one of interest here.

2. Transfer rates could possibly be better if you ensure that there is turbulence in the boundry layer, see https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021JG006520, which then would help minimize the potential problem mentioned in 1. I do acknowledge that that would increase the noise from the reactor.

3. Have you looked into the actual loss of flow due to the pressure of the gas in the reactor? The pressure of the CO2 in the reactor should be substracted from the head pressure of the pump and from there you can find the new theoretical flowrate. I am not going to go into the pressure losses due to friction and the additional loss of flow associated with that here. But to say that there are virtially no pressure losses/loss of flowrate from the reactor is not correct alone based on the additional distance needed for the water to move through the extra lenght of the hoses associated with the reactor.
I do acknowledge that increasing the diameter of the hoses can mitigate this, but that would be the same option for a setup without a reactor to reduce friction losses.

4. The size of the reactor is in my mind a problem, and if you want to diffuse CO2 into the aquarium without getting bubbles why not use a venturi injector? I designed one a few years ago and it ended up being 170 mm long and Ø 22 mm. It eliminates noise and there is no sintered glas diffusion that need cleaning. There are a lot of articles on venturi injectors, but as a start take a look at this: https://www.sciencedirect.com/science/article/abs/pii/S0144860921000121.

If you are interested in gas exchange between air and water I would recommend reading this doctoral thesis: https://gupea.ub.gu.se/bitstream/handle/2077/41805/gupea_2077_41805_2.pdf?sequence=2&isAllowed=y.

I think it is worth mentioning that making your own venturi injector is fairly easy, as far as I can tell just as simple as this reactor, but since it is smaller the material costs should be lower.
I am not using inline CO2 diffusion anymore as I like to see the fine bubbles move around the aquarium and dissolve. It helps me check that the flow is good and that I do not have dead zones in the aquarium.

 

[Pepere]

Have you looked into the actual loss of flow due to the pressure of the gas in the reactor? The pressure of the CO2 in the reactor should be substracted from the head pressure of the pump and from there you can find the new theoretical flowrate. I

Co2 pressure at the regulator is not going to affect the flow at all.

It releases bubbles in the reactor that displaces water until the gas bubble gets down to the outlet. It is not pressurizing anything…

Feet of head of flow also is not affected by how low the canister is below the tank either. That is because, unlike a sump, the feet of head of water coming don to the pump offsets the feet of head the water goes back up to the tank in the outlet. Unlike a sump, if you shut off the pump, the water in the hoses stay very near the top of the hoses.. sg
Hut off the pump in a sump and the water in the outlet hose will drain into the tank if there is not a check valve.

What will affect loss of head is the frictional losses of the pipe and fittings…. Going from relatively small pipe into a horizontal reactor that is substantially larger imposes turbulent flow and then going back into the smaller pipe also induces turbulence. Likely about the same as adding maybe 6-12 feet if hose…


Practically speaking the head loss in the short runs we are using on our tanks plumbing is pretty small….

I am absolutely thrilled with my Horizontal reactor…

 

[Max Power]

Co2 pressure at the regulator is not going to affect the flow at all.

It releases bubbles in the reactor that displaces water until the gas bubble gets down to the outlet. It is not pressurizing anything…

Feet of head of flow also is not affected by how low the canister is below the tank either. That is because, unlike a sump, the feet of head of water coming don to the pump offsets the feet of head the water goes back up to the tank in the outlet. Unlike a sump, if you shut off the pump, the water in the hoses stay very near the top of the hoses.. sg
Hut off the pump in a sump and the water in the outlet hose will drain into the tank if there is not a check valve.

What will affect loss of head is the frictional losses of the pipe and fittings…. Going from relatively small pipe into a horizontal reactor that is substantially larger imposes turbulent flow and then going back into the smaller pipe also induces turbulence. Likely about the same as adding maybe 6-12 feet if hose…


Practically speaking the head loss in the short runs we are using on our tanks plumbing is pretty small….

I am absolutely thrilled with my Horizontal reactor…

Have you measured this, because if the reactor is below the surface of the aquarium surface then there will be back pressure needed for running the reactor (hydrostatic pressure). For a good pump with a high head this is not really something to worry about, but outside the saltwater side of the hobby the head of all the pumps I have encountered is not that impressive, the best one I have experienced is the ADA Super Jet ES-2400

I will suggest that you take a look at this webpage (it is written by en engineer, so there are some omissions and it uses imperial not SI units, but for use by the average aquarist it is more that good enough): Visual Pump Glossary with regards to the additional 2 - 4 m of hose, look for the following sub headings; Colebrook equation, Darcy-Weisbach equation (those equations can with good approximation be replaced with the simpler Hazen-Williams equation for aquarium use as the fluid in our aquariums hopefully should have a viscosity fairly close to that of clean water), Reynolds number (Turbulent flow is when Re > 4000).
Once you have looked at the above and done a couple of calculations you might want to revise your statement regarding turbulent flow in the reactor. You should have turbulent flow in the hose, but not the reactor in general. As a side note, turbulent flow in the hose is not good with regards to friction losses, so the bigger diameter hose you use the higher flow you get, limited by the max flowrate of the pump.

Anyway if you are happy with your reactor that is all that should matter to you, but that does not change that the design could be improved and that it does have some drawbacks.

 

[Kwyet]

I’m not an engineer, but most reactors have something that impedes the flow—a diffuser or balls to churn it up, etc. This just goes from a tube to a larger tube and back to a smaller tube. It may impede the flow a small amount, but it seems to me that it’s better than anything else out there.

Some people do mount it above the aquarium. I don’t, because then as I understand it, overflow mode won’t work as well—more CO2 will dissolve as it’s traveling back down the tube instead of exiting quickly going up. There is some turbulence in the reactor, because I can hear it when I have the stand doors open. I have an fx4. Somewhere in the thread it was stated that use of an fx could be a little problematic because of the higher flow—noisier and waste some CO2. I get a series of fine bubbles every few minutes on overflow mode, instead of a single bubble. I could stop that by not using overflow mode, but I like the inherent safety.

If it gets surface film, I would think the people with clear ones would be able to see it. Even if not, after the CO2 is shut off, the bubble is absorbed and then the tube is completely filled with water passing through, which should clean it out.

 

[Pepere]

Have you measured this, because if the reactor is below the surface of the aquarium surface then there will be back pressure needed for running the reactor (hydrostatic pressure

That would be the case if you were running it from the output of a sump.

It most definitely does not apply if you are running it off of a canister filter.

The water coming down from the tank adds head to the pump that pushes it back up to tank level…

I dont need to measure it as it is basic hydronics and covered thoroughly in hydronic heating manuals.

We routinely install curculators that have 12 feetif head in multi story buildings that pump the water over 30 feet high with no problem because the pump does not have to overcome the height due to the weight on the water pushing down from the other side of the circuit doing the heavy lifting. The pump simply has to circulate the water and overcome frictional losses from the pipe and fittings…

When we design heating circuits for forced hot water circuit we convert fittings to extra feet of straight pipe. A 90 degree bend equivalent to 3 feet of pipe. A restriction down a size adds another so many feet of pipe and constricting down again adds a lesser amount than the expansion did. Valves imposes a certain number of extra feet of pipe.

The numbers it gives are rules of thumb that work close enough and were used for years and years before computerized hydronic calculator programs came in to being…

In any event the pressure of the co2 bubble in the reactor will be no higher than the pressure of the water in the reactor if there was no co2 injection. It will be determined by how many feet of head of water exists between the water surface in the aquarium to the reactor. In my case, likely around 1 1/2 psi, not the 40 psi My regulator is set at.

Lots of people have a very hard time wrapping their heads around the concept.

 

[Pepere]

If it gets surface film, I would think the people with clear ones would be able to see it. Even if not, after the CO2 is shut off, the bubble is absorbed and then the tube is completely filled with water passing through, which should clean it out.

I don’t think the co2 bubble ever gets completely absorbed between shutoff and restart in the morning.

 

[Kwyet]

I don’t think the co2 bubble ever gets completely absorbed between shutoff and restart in the morning.

Oh! I thought @Yugang said his was absorbed within 30 minutes. Mine isn’t clear. Thanks for the info.

 

[Yugang]

The main problem with this type of reactor would possibly be a buildup of a surface film during the injection phase

Transfer rates could possibly be better if you ensure that there is turbulence in the boundry layer

Just make sure there the water is not stagnant, this will make sure there is no surface film and there is sufficient turbulence. More flow is good, up to the point where it starts to make noise. The working of the reactor is virtually independent of the rate of water flow, as long as it is not stagnant.

Have you looked into the actual loss of flow due to the pressure of the gas in the reactor?

There is virtually no pressure of gas in the reactor, as it is an open system, and the water experiences virtually no back pressure.

The size of the reactor is in my mind a problem, and if you want to diffuse CO2 into the aquarium without getting bubbles why not use a venturi injector?

A horizontal reactor of a given size will generally have more power than a bubble reactor of same size.

I think it is worth mentioning that making your own venturi injector is fairly easy, as far as I can tell just as simple as this reactor, but since it is smaller the material costs should be lower

A venturi reactor will not be smaller, it will be larger. I have built a horizontal reactor that pushes 1.5 pH drop on my 50 gallons tank for in total 6 USD.

What will affect loss of head is the frictional losses of the pipe and fittings…. Going from relatively small pipe into a horizontal reactor that is substantially larger imposes turbulent flow and then going back into the smaller pipe also induces turbulence. Likely about the same as adding maybe 6-12 feet if hose…

It will we worse in a vertical bubble reactor, where the argument about friction and turbulence applies, but in addition to that the bubbles create a back pressure as if it were a reverse airlift pump. A horizontal reactor has virtually no pressure loss.

Anyway if you are happy with your reactor that is all that should matter to you, but that does not change that the design could be improved and that it does have some drawbacks.

You may want to read the previous posts this thread, as frankly none of your arguments in previous points have been correct. Granted, some of your ideas are qualitatively correct, but not quantitatively or based on any calculations or experiments.

If you are not using reactors anymore and like the bubbles in your tank, as you say, I may kindly suggest not to invest more time for horizontal reactors.

the design could be improved

Please let us know your ideas.

I don’t think the co2 bubble ever gets completely absorbed between shutoff and restart in the morning

The gas pocket that remains is not CO2, it is the gas that diffuses back from water into the CO2 pocket. This is a consequence of Henry's law, and is a sign that we could increase CO2 flow a bit and have overflow mode work better.

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

Oct 8, 2023

Context

As described earlier, we could operate the reactor in three different ways

• Using a pH/CO2 controller for CO2 injection and stability
• Using a precision CO2 regulator to precisely adjust CO2 injection
• Overflow mode.

Most current users are either using a pH/CO2 controller or a precision CO2 regulator. There will be a reservoir of almost pure CO2 gas in the reactor, and the physics/chemistry of CO2 absorption into the water will be similar to any other reactor that may or may not use CO2 bubbles. As is also the case in bubble reactors, gradually we...

• Yugang

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[Pepere]

The gas pocket that remains is not CO2, it is the gas that diffuses back from water into the CO2 pocket. This is a consequence of Henry's law, and is a sign that we could increase CO2 flow a bit and have overflow mode work better.

Good to know. Is it a mix of co2 and air, or just air?

I have tested my tank waters ph right before solenoid opens up and I am measuring 0.6 ph drop from a degassed sample, hence there must be significant co2 in the tank left from the prior day.

 

[Yugang]

Good to know. Is it a mix of co2 and air, or just air?

When the reactor operates with a nearly pure CO2 pocket, by Henry's law gases will diffuse back from the aquarium water into that gas pocket. So we may assume it is mainly nitrogen and oxygen. At the end of the day CO2 gets easily absorbed into the aquarium, but these other gases have built up during the day and will only slowly dissolve back until Henry's law equilibrium is achieved again. In the post quoted above, I calculated this whole process, and found that perhaps 5-10% rate of overflow will keep the gas pocket nearly perfectly clean CO2 and have the reactor automatically purge itself. Bubble reactors have the same back diffusion, but unlike horizontal reactor to gas pocket continues to build up and does not purge itself.

As explained earlier in this thread (for example #156) I use the size of the gas pocket at the end of the day as a measure if overflow mode has been optimised. Besides that I also check how often small bubbles escape (one or two times per minute or so), or the bubble count injected, so a transparent reactor is a nice to have, but not a necessity.

there must be significant co2 in the tank left from the prior day.

This is normal. That is why we need the pH drop from degassed sample, and not from the tanks' morning water that still contains significant CO2

 

[Max Power]

So far there have been quite a few replies, but no documentation although some interesting personal observations.

If the ‘air’-pocket inside the reactor never goes completly away during the CO2 off period, then the surface film that can form due to, most of the time, protein buildup associated to insufficient maintenance, will most likely not be removed and therefore reduce the transferrates in the reactor.
The reactor design could be changed to mitigate this potential buildup, as well as some of the headloss introduced due to the less than optimal geometry of the reactor (see: http://www.sapub.org/global/showpaperpdf.aspx?doi=10.5923/j.am.20130305.02). Do this by having the inlet to the reactor at the top of the reactor cavity and the outlet at the bottom of the reactor. At the same time ensure that the internal walls of the reactor slopes towards the inlet and outlet openings. This will minimise the noise from water splashing, but at the same time give a slight skimmer effect where the water running down the slope enters the main body of slower moving water in the reactor. An added bonus to the sloped part will be an increased CO2 uptake.
Another modification to the reactor would be to use a highly oval crosssection pipe for the reactor cavity to reduce the headloss from the ‘air’-pocket, but that would be hard to get hold of, so make it a flat box.

I would say that if making the above design changes to the reactor you might as well make a venturi injector instead due to the manufacturing proces' involved, but that is not what you are looking for, so…


With regards to the headloss due to the ‘air’-pocket I can not provide free links to the textbook material I refer to in my professional life, but look at the following link: http://www.sapub.org/global/showpaperpdf.aspx?doi=10.5923/j.ijhe.20180703.02, for an easy to understand article.

@Yugang , you live in China so I think that you would have better access to a lot higher volume of the research coming out of CAS on venturi injectors. Back when I looked into how best to design them for use in aquarium setups, CAS seemed to be where the majority of the good research was done.

 

[Yugang]

the surface film that can form due to, most of the time, protein buildup associated to insufficient maintenance, will most likely not be removed and therefore reduce the transferrates in the reactor.

This is a hypothetical problem, that has never been observed by me or any other user. It would be great if you could launch your own ideas in CO2 injection and Venturis that help the hobby, and perhaps you could start a separate thread on that where I would be happy to contribute and build on your ideas.

For the sake of the theoretical exercise, starting from an imaginary problem, let us then evaluate an experiment in which we inject olive oil in the reactor during the night. How will the reactor solve this hypothetical situation?

• Early in the morning, when CO2 starts, the efficiency of CO2 absorption from the gas pocket into the water will be reduced by the layer of olive oil.
• The gas pocket will grow, as less gets dissolved, until the point that the reactor is in overflow mode.
• In overflow mode, the olive oil will be sucked into the water exit, just as small bubbles of gas will be purged.
• When all olive oil has been sucked up, the reactor water / gas pocket interface is perfectly clean and with some reasonable turbulence.
• Hypothetical problem solved, and we have the reactor perfectly clean in overflow mode where it will stabilise CO2 injection.

So far there have been quite a few replies, but no documentation

I am not using inline CO2 diffusion anymore as I like to see the fine bubbles move around the aquarium

Understand that reactors are not your thing, however if you have some concrete questions after reading the thread please reach out to me by PM. I have lost count how many hobbyists are using the horizontal reactor, and enjoy helping as many as I can with practical and constructive advice based on calculations, tests and practical experience as a physicist.

 

[Naturescapes_Rocco]

So far there have been quite a few replies, but no documentation although some interesting personal observations.

If the ‘air’-pocket inside the reactor never goes completly away during the CO2 off period, then the surface film that can form due to, most of the time, protein buildup associated to insufficient maintenance, will most likely not be removed and therefore reduce the transferrates in the reactor.
The reactor design could be changed to mitigate this potential buildup, as well as some of the headloss introduced due to the less than optimal geometry of the reactor (see: http://www.sapub.org/global/showpaperpdf.aspx?doi=10.5923/j.am.20130305.02). Do this by having the inlet to the reactor at the top of the reactor cavity and the outlet at the bottom of the reactor. At the same time ensure that the internal walls of the reactor slopes towards the inlet and outlet openings. This will minimise the noise from water splashing, but at the same time give a slight skimmer effect where the water running down the slope enters the main body of slower moving water in the reactor. An added bonus to the sloped part will be an increased CO2 uptake.
Another modification to the reactor would be to use a highly oval crosssection pipe for the reactor cavity to reduce the headloss from the ‘air’-pocket, but that would be hard to get hold of, so make it a flat box.

I would say that if making the above design changes to the reactor you might as well make a venturi injector instead due to the manufacturing proces' involved, but that is not what you are looking for, so…


With regards to the headloss due to the ‘air’-pocket I can not provide free links to the textbook material I refer to in my professional life, but look at the following link: http://www.sapub.org/global/showpaperpdf.aspx?doi=10.5923/j.ijhe.20180703.02, for an easy to understand article.

@Yugang , you live in China so I think that you would have better access to a lot higher volume of the research coming out of CAS on venturi injectors. Back when I looked into how best to design them for use in aquarium setups, CAS seemed to be where the majority of the good research was done.

As someone who has used every reactor and diffuser under the sun, the "pro:con" ratio of the horizontal reactor is by far the best I've ever used, and I'm unlikely ever to go back to vertical or flow-based reactors of any kind.

I'd suggest giving it a try yourself before presenting more hypothetical issues. Nothing you've suggested or presented has been an issue for anyone I've seen, read, or spoken to. I'm sure you're trying to be helpful to improve the design, but it's already quite a simple design and there's not much to improve.

It's an extremely well-designed device for dissolving CO2 into our tanks with as few issues as possible. It's silent, unbelievably efficient, independent of flow rate, easy to DIY (perhaps the easiest I've ever made), requires no maintenance, and has built-in adjustable safety features to prevent over-gassing. The only genuine "con" is the size/space required, because they can be large.

If you'd like to learn more, I have two threads:

• Testing the Aqua Rocks Colorado Acrylic Horizontal CO2 Reactor on a large tank
• Easy and Cheap DIY Horizontal reactor (Yugang Reactor) from an existing vertical reactor

I've been using these for a while now, so let me know what real-world questions you may have about their operation!

 

[Unexpected]

most of the time, protein buildup associated to insufficient maintenance, will most likely not be removed and therefore reduce the transferrates in the reactor.

This never occurs and I have a clear reactor and has not been cleaned in 6 months and I can see bacterial build up. PH changes is always the same and I have minimal flow through the reactor with only visible ripples when the reactor reaches overflow mode. No one has been running Yugangs reactor longer than me and have a non clear reactor running on a different tank for over a year and have never cleaned it.
It's the same day in and day out and I litterly don't think about CO2 anymore.

This will minimise the noise from water splashing,

What noise, what splashing? I'm in not sure you know how this reactor functions.