# CO2 Spray Bar



## Yugang (24 May 2022)

The fancy term ‘CO2 reactor’ suggest something magical is going on, but essentially it is a tube filled with water and bubbles, where the surface area of the bubbles drives the absorption of CO2 gas in the flow of water.
My own CO2 reactor (modified Aquamedic with bypass) has been working perfectly for several years and was not worth spending any more time on. Well, until recently, when I took pictures and estimated the surface area of CO2 bubbles and came to some new insights.

I have been experimenting with a new CO2 setup, that I would call “CO2 spray bar”.
It works so well, that I am not sure if I will use my reactor again (I have given up on CO2 diffusors long time ago).







The full length of my tank has a spray bar for filter water return, that creates a gentle surface flow to the front with some surface agitation. The water then goes down and returns via the bottom to the back again and then upwards.
The CO2 spray bar is a half-pipe over the full tank length, filled with CO2. It is open at the bottom where it creates an absorption surface to the water flow. Mounted just below the spray bar is the CO2 bubble source, so that bubbles float up and replenish the reservoir in the spray bar.
Absorption at the open bottom of the CO2 spray bar enriches the waterflow, which goes straight down to the plants, homogeneous over the full length of the tank.

Benefits

No need for CO2 reactor (expensive, slows filter flow), or diffusors (stability, maintenance).
No need for expensive precision regulator. The CO2 absorption is proportional to the surface area of the CO2 spray bar, which is constant when entirely filled with gas. The regulator has no role, other than supplying just enough CO2 to keep the spray bar full. Set regulator 10% exceeding CO2 absorption, so that once a while an excess bubble escapes from the reservoir yet keeps it fully filled
Safe for life stock. When too much CO2 is injected, the spray bar will overflow and release bubbles to surface of tank. pH/CO2 ppm is not affected at all.
Cheap. Just some plastic parts and glue.
Can be used with pH controller as well. The inherent safety of the CO2 spray bar mitigates several risks associated with pH control. Benefit is that a pH controller allows fast ramp up, and mitigates the impact of variations in surface agitation.

Full tank shot. As I used transparent plastic for both spray bars, at water surface, the CO2 spray bar is hardly visible.





Top and bottom shots of CO2 Spray Bar







Performance







pH stable within 0.1 between 10:00 AM and 14:00, when CO2 is switched off. 14:15 CO2 Spray Bar half empty, and pH starts to rise again. Drop checker lime green and plants pearling. Fish happy.

Design rules / estimation
For my tank (100 * 45 * 60 cm) I use a 1 inch, 90 cm long CO2 spray bar This is 216 cm2 surface area. The ratio between tank surface area (4500 cm2) and CO2 spray bar (216) is 20.8 :1. For other tank dimensions, this ratio is a good approximation how to find the optimal dimensions of the spray bar.

Notes:

Still contemplating another concept, that will be outperforming dream machine, not to mention traditional CO2 controllers. Perhaps it is best to collect some more data on CO2 spray bar to better understand if a more technology heavy approach makes any sense at all. Still excited about the other concept though, may introduce that later.
Hope that others can verify the CO2 spray bar concept in their tanks, and post data on this thread, as I can still hardly believe my observations and the strengths of such a simplistic concept. It will also help validate the concept for different tank sizes, water flows and planting.
Hope you all enjoy, and perhaps build one yourself


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## Ria95 (24 May 2022)

Thanks for sharing. The build looks clean. The description essentially sounds like a passive CO2 diffusor.

It might be worth  considering adding a degas valve at the top like some of the bell diffusers have to let out from time to time the "air" at equilibirum with the tank. This  can accumulate over time and reduce the efficiency.


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## KirstyF (24 May 2022)

Yugang said:


> The fancy term ‘CO2 reactor’ suggest something magical is going on, but essentially it is a tube filled with water and bubbles, where the surface area of the bubbles drives the absorption of CO2 gas in the flow of water.
> My own CO2 reactor (modified Aquamedic with bypass) has been working perfectly for several years and was not worth spending any more time on. Well, until recently, when I took pictures and estimated the surface area of CO2 bubbles and came to some new insights.
> 
> I have been experimenting with a new CO2 setup, that I would call “CO2 spray bar”.
> ...



Interesting concept @Yugang.

I note ur PH drop goes as high as 1.6. Have you played with sizes of the Co2 ‘spraybar’ tubing at all, to achieve lower levels? (As many fish keepers like to keep inside the 1ph level for safety) 

Also, my understanding (and correct me if I’m wrong) is that the quantity of Co2 being delivered to/absorbed by the water will be directly related to the surface area made available by the tubing size and therefore adjustment of the Co2 level could only be achieved by changing the pipe size!!? 

If so then alternatively, if you utilised a triangular shaped pipe, the Co2 surface area and subsequently the absorption level would increase/decrease depending on how full that pipe was, would it not? This would still require the ability to either finely tune delivery of the Co2 to maintain a very specific level (potentially defeats the object of some of your benefits) or some sort of adjustable overflow that could be set to allow excess Co2 to escape at a particular point?  Don’t think that would be too tough to engineer! 

Just thoughts really but I feel maintaining the ability to easily adjust the Co2 level would be a ‘must have’ for a lot of folks!


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## Yugang (24 May 2022)

Ria95 said:


> It might be worth considering adding a degas valve at the top like some of the bell diffusers have to let out from time to time the "air" at equilibirum with the tank. This can accumulate over time and reduce the efficiency.


Perhaps, but I suggest to wait for further user experience and see if indeed efficiency is significantly reduced (in my experience, no problem here). Degassing the CO2 spray bar is as easy as rotating it 90 degrees and back, which I do at weekly water change anyway 



KirstyF said:


> I note ur PH drop goes as high as 1.6. Have you played with sizes of the Co2 ‘spraybar’ tubing at all, to achieve lower levels? (As many fish keepers like to keep inside the 1ph level for safety)


Yes, I built several prototypes, each at 40 HKD (4 GBP) materials cost. Some shorter, some longer, all with different pH drop result. .
I used this 1.6 drop in my posting as a proof of concept, indeed a slightly shorter bar may give a safer 1 pH drop for the average user and tank setup.
Although it is not beginners advice, several users (@GreggZ       pH 1.4 drop     ) are higher.  In my tank the Rasbora's  first give warning signs (while tetras and Otto are fine), but can still go to a slightly yellow drop checker without any complaint from them.



KirstyF said:


> finely tune delivery of the Co2 to maintain a very specific level


The easy way is to use some transparent tape from the office supplies shop and with that reduce the surface area at the bottom of the spray bar. 1 cm tape on a 90 cm spray bar yields a 1% reduction in CO2 absorption. I have also partially filled my circular tube, same thing as you suggest with the triangular shape, but then we need again a precision CO2 regulator 



KirstyF said:


> Just thoughts really but I feel maintaining the ability to easily adjust the Co2 level would be a ‘must have’ for a lot of folks!


it is as simple as this


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## Yugang (28 May 2022)

Continued testing.

A drop checker mounted 10 cm from the bottom on the front (i.e. in the path of the spraybar) is going into the yellowish green, and for pH drop I  consistently measure 1.5-1.6. Fish are ok, but I believe I should not go to even higher CO2 ppm.

If anything, I would change the spraybar to a slightly smaller size, and lower CO2, but for the rest it works very well. I am now using an old regulator, with a stability that I did not consider acceptable anymore for my reactor, but for the spray bar I don't bother about regulator precision.

With one or two more weeks of testing of the spray bar I may decide to disassemble the (not active since installing spray bar) reactor, and store it. Really not sure why I would ever use it again.


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## Yugang (5 Jun 2022)

A FTS by night. Huge windows and HK sunshine are a challenge making daytime pictures. Nightime with dimmed light and more relaxed fish is my favorite anyway.





Nice progress with testing my CO2 Spay Bar, but playing with CO2 always comes at a cost. I may need a few more weeks, some adjustments here and there, and hope to share my experience later on.


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## Nick potts (5 Jun 2022)

This is similar to what tropica and few others offer but with a better reservoir design and constant refill.

Tank looks good and good luck with the experiment.


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## Yugang (5 Jun 2022)

Nick potts said:


> similar to what tropica and few others offer


Would be nice to learn from what others have done, could you give a link please?

EDIT: Checking out Tropica website again and only find CO2 system with diffusor. This would be my least favourite (maintenance, stability, efficiency) method.  Am I missing something @Nick potts , and could you help me please with links to similar solutions as you mention?


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## Yugang (11 Jun 2022)

Although my CO2 Spray Bar has been working fine since first installation in my tank, I continued with testing over the past few weeks with two objectives:

I am probably not alone in being surprised that such a simple and powerful concept has not been developed before, and want to be sure there are no hidden problems or roadblocks. If ultimately it wouldn’t appear practically feasible, I would prefer to report that asap, forget the CO2 Spray Bar and go back to using my CO2 reactor.
I hope that measurement data and detailed description can save time when implementing the concept in other tanks. We already have 3.6K CO2 threads, and have still not managed to demystify CO2. With a detailed description, CO2 Spray Bar can be simple and in my experience superior to diffusers and even reactors, with or without CO2 controller.

*CO2 overflow*

In the original design my Spray Bar would always be fully filled with CO2, with excess CO2 escaping at irregular intervals and with larger blurbs from the open bottom of the bar. I modified the design with a 5 mm hole (‘CO2 overflow’) as per below:





The water/CO2 meniscus is visible in the CO2 overflow, and small excess amounts of CO2 will escape at regular intervals (usually 30-120 seconds, depending on CO2 regulator setting). With this overflow I can optimise the CO2 regulator setting so as to minimize unnecessary CO2 losses, as well as the setting the dimensions of the CO2 reservoir by turning the white piece clockwise (less CO2 reservoir) or counter clockwise (more). With my current setting of the CO2 overflow I get a 1.4 pH drop, so I won’t change it anymore and pH drop will be stable over time within a few hundedths.

Note: if the CO2 overflow is drilled too small, less than 5 mm, it will not work anymore as the surface tension on the water will not allow bubbles to form under the low working pressure. 5-6 mm, and in this position works well, but I would be happy with a smart idea how to create even smaller bubbles from the overflow to further minimize losses.

*Setting up the spray bar and CO2 regulator.*

During weekly tank maintenance I take the CO2 Spray Bar out, as it is a bit fragile and I want to save myself an hour work and 4 GBP producing a new one.

Placement back in the tank takes less than a minute, using the trick to align the top of the Spray Bar exactly with the water surface.

As per the first posting in this thread, setting of the CO2 regulator is no longer precision work. Everything is fine and pH is perfectly reproducible as long as the Spray Bar remains full and there is some excess from the overflow. Just inject enough and watch the overflow releasing CO2 at some intervals, then dial down regulator only to save on CO2 consumption. I usually set CO2 regulator anywhere between 5 and 6 bps and don’t worry about further finetuning.

*Testing stability / reproducibility*

The benefit of the spray bar is that we do no longer need a precision CO2 regulator. I usually inject 5 or 6 bps into the spray bar. With 5 bps the spray bar fills slowly in the morning, and releases just one bubble per 60-90 seconds from the overflow after stabilisation. When I increase injection to 6 bps the Spray Bar will start releasing CO2 less than 1 hr after start up, and later on release CO2 from the overflow every 15-30 sec.

pH profile compared on day 1 with 5 bps, and day 2 with 6 bps. Degassed pH = 7.4, so both stabilize at 6.0 which is a 1.4 pH drop.
In all graphs I use raw data, no corrections. For some reason the starting pH on one morning is 6.52, other morning 6.73.
For a fair comparison of both curves we could measure the time from 6.5 down to 6.1, which is 3 hrs for both days. pH stabilises at 6.0 and remains within plus or minus 0.01 during the day, irrespective of CO2 regulator setting.





*Full day pH curve*

As the lowest pH is 6.0 with my current spray bar and setting of CO2 overflow, it is preferred to keep pH within 6.1 and 6.0 during the photo period. As discussed above generally 3 hours CO2 before lights on will be sufficient to reach 6.1. In the below graph I turned CO2 off at 14:00, and this allows 2 more hours during the photoperiod until the pH crosses the 6.1 level. After CO2 injection off, the Spray Bar gradually empties within typically 30 min.

(Note: have no explanation for the pH 0.02 irregularity at 15:15 )





In summary, I turn CO2 on 3 hours before photo period, off 2 hours before end of photo period.

*Need for air release?*

Most CO2 reactors have a valve to release air. This air may otherwise accumulate, creating noise and reduce efficiency.

I have not noticed significant issues with air build up in my spray bar, other than when I introduced bubbles topping up tank water from a bucket.

There are two easy ways to get air out from the spray bar. Turn it 90 degrees and back, or use a turkey blaster to suck it out. Both are quick and efficient, but the question remains if it is necessary at all.

When there is air trapped in the CO2 Spray Bar, the CO2 partial pressure will be lowered and efficiency of absorption in water is lowered as a result. However, with lower CO2 uptake by water, the reservoir volume grows quicker and the CO2 overflow releases bubbles faster. With each bubble that escapes the reservoir from the overflow, some air is purged out as well. Effectively, the more unwanted air is still present, the faster the CO2 Spray Bar gets rid of it.

I decided to test the theory with an extreme experiment – I filled the Spray Bar with 100% air in the early morning, just to see what happens. The result is remarkable, even with the extreme 100% air filling the pH curve is within a few hundredths of what it would be without any air. Actually the physics behind is more complicated than the graph suggests, I did some literature search as well, but will not elaborate on that in this posting. They key result is that the CO2 Spray Bar deals with trapped air through its operating principle, and the user does not need to worry about at all.


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## Nick potts (11 Jun 2022)

Yugang said:


> EDIT: Checking out Tropica website again and only find CO2 system with diffusor. This would be my least favourite (maintenance, stability, efficiency) method. Am I missing something @Nick potts , and could you help me please with links to similar solutions as you mention?








						Aquarium CO2 Kits, CO2 and Planting Equipment
					

CO2 and Planting Equipment plus free next day delivery options and 60 day returns.




					www.swelluk.com


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## Yugang (11 Jun 2022)

Nick potts said:


> Aquarium CO2 Kits, CO2 and Planting Equipment
> 
> 
> CO2 and Planting Equipment plus free next day delivery options and 60 day returns.
> ...


Not longer offered by Tropica brand. Will not be a reliable CO2 solution for most tanks, and does not bring  same benefits as CO2 Spray Bar.


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## Nick potts (11 Jun 2022)

Yugang said:


> Not longer offered by Tropica brand. Will not be a reliable CO2 solution for most tanks, and does not bring  same benefits as CO2 Spray Bar.



Can still be bought and other companies offer the same.

While I agree not the same as your bar, it operates on exactly the same principle, passive diffusion of CO2 into the water column. 

I also don't think the bar will offer a reliable and simple solution to most tanks compared to even budget reg and needle valve.


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## Gorillastomp (11 Jun 2022)

Your system is interesting. I think this could be inserted in a sump without reducing the flow that the reactor brings in.
 Probably less effective than a reactor for dropping the PH quicker.


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## Yugang (12 Jun 2022)

I hope it is helpful to give a summary.

I tested various CO2 regulators,  in-tank and in-line diffusers over the years, and most recent years worked with a reactor that I modified. For the CO2 Spray Bar I invested quite some time, and posted the measurement results in this thread for the benefit of other hobbyists.

From my experience (partially subjective, mostly based on facts and experience) I now believe that CO2 Spray Bar outperforms diffusers and reactor on almost all parameters.





I have decided to disassemble the reactor I have been using for years, which always worked very well. I am using my pH/CO2 controller now only for measuring CO2 profiles, but frankly see no benefits anymore using it to control my CO2 injection again.

The performance and benefits of my Spray Bar are too obvious and convincing for me, and I doubt if I will ever use my reactor (or pH controller) again.

If for some reason I get less happy with my CO2 Spray Bar, I will share with an update on this thread.

Thank you for reading!

_P.S. I hinted in other threads that I have ideas for a new CO2 concept, that will outperform traditional regulators and even CO2 dream machine. _
_With CO2 Spray Bar however, I am not sure anymore if longer term there is a need in the hobby for more advanced technological concepts, regulators, diffusers or reactors. _
_I will let the CO2 Spray Bar ideas sink in, hopefully some others build one and share their experience, and later on decide if and how I share my other ideas._






CO2 Spray Bar nearly invisible...


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## Andy Pierce (12 Jun 2022)

Do you find the CO2 concentration is dependent on how much flow there is over the bar?  If you slow down the flow, does that decrease the amount of CO2 in the water?


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## Yugang (12 Jun 2022)

Andy Pierce said:


> Do you find the CO2 concentration is dependent on how much flow there is over the bar?  If you slow down the flow, does that decrease the amount of CO2 in the water?


I have not been able to test that, but I suspect that any reasonable flow will do. When I take spray bar out, mount is again, or change direction of water spray bar I find very little to no variation on pH profile.

From a physics perspective - stagnant water will create a boundary layer that will slow down absorption. But I would expect that any reasonanble flow will eliminate that effect and soon create a stable situation where only the surface area counts. 

As said, day to day I find pH reproducible within 0.01 or 0.02, even after some adustments in the tank.


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## Andy Pierce (12 Jun 2022)

Since the CO2 is dissolved in the water (rather than suspended temporarily as bubbles) I suppose it wouldn't matter where the CO2 bar was with respect to the water spray bar... you could probably but them both together at the back of the tank for a cleaner look.  If the rate of the flow doesn't matter, it could be straightforward to calculate how much CO2 surface area you needed for a tank of any specified water volume.
You show the pH drop during the day, but how do you turn the CO2 spray bar off?  Do you stop the water flow at night, or does the CO2 empty itself after you stop bubbling CO2 into the spray bar?


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## Yugang (12 Jun 2022)

Andy Pierce said:


> you could probably but them both together at the back of the tank for a cleaner look


I thought about mounting it on the back, valuable point. However at the front it is hardly visible, and I like the efficiency of dissolved CO2 going straight down to the plants, rather than having to travel the surface from back to front first.



Andy Pierce said:


> it could be straightforward to calculate how much CO2 surface area you needed for a tank of any specified water volume.


The required surface area of the CO2 spray bar should be proportional to the surface area  of the tank, not the volume. This is because outgassing of CO2 from tank surface is the main factor to determine the equilibrium CO2 ppm. Hope this is clear, I am happy to elaborate further. The volume of tank then comes into play in the speed of the ramp up in the morning.



Andy Pierce said:


> You show the pH drop during the day, but how do you turn the CO2 spray bar off? Do you stop the water flow at night, or does the CO2 empty itself after you stop bubbling CO2 into the spray bar?


I stop the CO2 bar by turning solenoid off, 2 hours before I start dimming light.
Filter continues at night, spraybar is mostly empty some time after solenoid off.


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## LMuhlen (27 Jun 2022)

I'm following your experiment and am itching to try it. But I feel that you didn't list in your table 2 important restrictions of the system, which are maybe prohibitive for me.

First it is closely tied to the filtration return being back to front. I can't do that in my setup, so the reactor gets a point here, it doesn't care how the water returns, there just needs to be circulation. I could use a spray bar, but it would need to be from side to side and the flow would probably lose its coherence when it reached the other side.

Second, it seems like it would suffer from evaporation and with the water level reducing. Again, the reactor doesn't care. So another point for the reactor.

I would add a line in your table with something like setup flexibility, where it loses to the alternatives. Still, I think it has many positive characteristics and I'm trying to find a creative solution to implement it here somehow.


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## Yugang (27 Jun 2022)

LMuhlen said:


> First it is closely tied to the filtration return being back to front. I can't do that in my setup, so the reactor gets a point here, it doesn't care how the water returns, there just needs to be circulation. I could use a spray bar, but it would need to be from side to side and the flow would probably lose its coherence when it reached the other side.


This is correct. I believe that generally one needs a filter return spraybar over the full length of the tank, and the CO2 Spray Bar over full tank length as well.
For the CO2 Spray Bar to have suffcient capacity I believe the design rule in the OP is still roughly correct:


Yugang said:


> Design rules / estimation
> For my tank (100 * 45 * 60 cm) I use a 1 inch, 90 cm long CO2 spray bar This is 216 cm2 surface area. The ratio between tank surface area (4500 cm2) and CO2 spray bar (216) is 20.8 :1. For other tank dimensions, this ratio is a good approximation how to find the optimal dimensions of the spray bar.


As @Andy Pierce noted, the CO2 Spray Bar could probably also be mounted on the back if that would be preferred.

While I understand that full length spray bars are not suitible for every tank, they have a big plus in terms of flow and distribution if they can be used.  This was already  known before I started thinking about the CO2 aspect. With a transparent tube they can be virtually invisible as you see from my FTs.



LMuhlen said:


> Second, it seems like it would suffer from evaporation and with the water level reducing. Again, the reactor doesn't care


This is actually my focus in the past several week's experiments. The point is, a reactor DOES care as do all setups that do not use a pH controller for stabilisation
In a traditional setup (no pH controller)   CO2 is a balance created between injection, outgassing and consumption in the tank. This is irrespective of injection method (reactor, diffuser, spray bar).

The tank's outgassing is very sensitive to variations of surface agitation and flow, but no more for a CO2 Spray Bar than for a reactor or diffuser. I also learn that actually the morning's starting pH (as a result of outgassing but also plant and fish CO2 production during the night) can be quite variable

The CO2 Spray Bar does not care too much about water level, as long as it remains below water.

What I am currently monitoring is how I get the smallest (few 0.01 pH) day-to-day variations in CO2 ppm. I suspect that nearly nobody in the hobby manages this well. From my experience this challenge is no different with a CO2 Spray Bar than diffuser or reactor, it is inherent in the CO2 balancing act in the tank, when not using an active controller.

Until now I am using my pH/CO2 controller only as a pH monitoring device, but not to control the solenoid. If I actually start to control the CO2 system with Spray Bar the CO2 stabilisation problem is solved by the controller, while the CO2 Spray Bar provides the inherent safety for cases where the controller would fail and try to inject too much CO2.


LMuhlen said:


> I would add a line in your table with something like setup flexibility, where it loses to the alternatives.


I had a perfectly working reactor in my tank, but decided to disassemble and not longer using it. From my experience, and this is for my tank, the spray bar is better and I see no flaws that I wouln't have with reactor of diffuser.
My only doubt today is whether I would prefer a system with pH/CO2 controller (so easy to stabilise, but some points of potential failure), or just the CO2 spray bar with a simple CO2 regulator (needs a bit more experience to get  CO2 stability over days and weeks).


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## Hanuman (28 Jun 2022)

Kudos for the putting time and effort into trying something new. I have to say you went full bore with this and whether it works out or not at the end you did it for the sake of passion to the hobby. 👍

So far the only real drawback I see from this is the addition of yet another piece of hardware inside the tank specially at the front which can be an eye sore for some. Other than that it seems effective but one small note, I think one needs to slightly oversize the bar from inception (one way or another, either length or diameter wise) else you end up with a less than desirable PH drop since the geometry is fixed and you have an overflow which would prevent PH dropping further, assuming you have proper surface agitation, of course. One would then need to decrease the efficiency of the bar by adding something to decrease the surface area of waters/co2 to adjust it, just like you did by adding the tape.


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## Yugang (28 Jun 2022)

Hanuman said:


> Kudos for the putting time and effort into trying something new. I have to say you went full bore with this and whether it works out or not at the end you did it for the sake of passion to the hobby. 👍
> 
> So far the only real drawback I see from this is the addition of yet another piece of hardware inside the tank specially at the front which can be an eye sore for some. Other than that it seems effective but one small note, I think one needs to slightly oversize the bar from inception (one way or another, either length or diameter wise) else you end up with a less than desirable PH drop since the geometry is fixed and you have an overflow which would prevent PH dropping further, assuming you have proper surface agitation, of course. One would then need to decrease the efficiency of the bar by adding something to decrease the surface area of waters/co2 to adjust it, just like you did by adding the tape.


Thank you for your kind words @Hanuman



Hanuman said:


> So far the only real drawback I see from this is the addition of yet another piece of hardware inside the tank specially at the front which can be an eye sore for some


You can hardly see it when the lights are on. In fact only the three suckers to the glass. The tube is virtually invisible, is obvious only at night when lights are off.



Hanuman said:


> I think one needs to slightly oversize the bar from inception (one way or another, either length or diameter wise) else you end up with a less than desirable PH drop since the geometry is fixed and you have an overflow which would prevent PH dropping further, assuming you have proper surface agitation, of course. One would then need to decrease the efficiency of the bar by adding something to decrease the surface area of waters/co2 to adjust it, just like you did by adding the tape.


Actually mine is oversized, it gives a 1.6 pH drop at full capacity.
I am using the below end piece to create a smaller CO2 reservoir in the tube, reducing its power to 1.4 pH drop. By rotating the end piece clockwise I push the CO2 meniscus up and can further reduce power.






I have some excess bubble escape from here every few minutes, this is how I guarantee that the reservoir is always filled to the same level, while minimising CO2 loss. As long as I see some excess CO2 escaping, I don't care about the precise setting of my CO2 regulator as I know that injection from the bar into the water is a constant.


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## Hanuman (28 Jun 2022)

Yugang said:


> ou can hardly see it when the lights are on. In fact only the three suckers to the glass. The tube is virtually invisible, is obvious only at night when lights are off.


Well this is arguable and I am pretty sure that on display tanks it would bother some. One way of minimizing the sucker view but also of making the bar more future proof, is by having adjustable height hooks that hold the bar from each side instead of having suckers in the front. This would also be safer as suckers can also sometimes slide/drift when they get older.


Yugang said:


> I am using the below end piece to create a smaller CO2 reservoir in the tube, reducing its power to 1.4 pH drop. By rotating the end piece clockwise I push the CO2 meniscus up and can further reduce power.
> 
> 
> 
> ...


Yes was actually going to comment on that. Having a rotary end piece enables you to adjust the contact surface since it's a cylinder. 👍
Here is an improvement you can do to make it safer and more reliable. The rotary cap could have clicking notches with some graduation to make it easy to visualize and assure you are always at the setting you want it to be.


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## Yugang (28 Jun 2022)

Hanuman said:


> Well this is arguable and I pretty sure than on a display tanks it would bother some. One way of minimizing the sucker view but also of making the bar more future proof, is by having adjustable height hooks that hold the bar from each side instead of having suckers in the front. This would also be safer as suckers can also sometimes slide/drift when they get older.


Agree. BTW, I take the bar out at each maintenance, replace it afterwards. Perhaps in the future we mount it on the back, just under the water spray bar, but here we lose the benefit of the dissolved CO2 going straight down with the water flow to the plants.



Hanuman said:


> Yes was actually going to comment on that. Having a rotary end piece enables you to adjust the contact surface since it's a cylinder. 👍
> Here is an improvement you can do to make it safer and more reliable. The rotary cap could have clicking notches with some graduation to make it easy to visualize and assure you are always at the setting you want it to be.



Here they are, you see the black dots? I use these to precisely reproduce my rotation settings 
From the top view you can also see the meniscus of CO2, and that indeed the bar is only about 60%-70% filled.


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## Hanuman (28 Jun 2022)

Yugang said:


> Perhaps in the future we mount it on the back, just under the water spray bar, *but here we lose the benefit of the dissolved CO2 going straight down with the water flow to the plants.*


Not sure it will change anything. In my opinion, having the bar under the spray bar wouldn't be detrimental because the flow momentum would carry automatically the CO2 charged water up to the spraybar and accros the tank again. It's a circular motion so whether in front or at the back I don't think it will change much if anything. Try it and let us know.


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## Yugang (28 Jun 2022)

Hanuman said:


> Not sure it will change anything. In my opinion, having the bar under the spray bar wouldn't be detrimental because the flow momentum would carry automatically the CO2 charged water up to the spraybar and accros the tank again. It's a circular motion so whether in front or at the back I don't think it will change much if anything. Try it and let us know.


You are most likely right on this one, although I still have some doubts how much efficiency would be lost due to increased outgassing.

If like you, most people worry about mounting on the front, I may have to give priority testing it on the back. For me personally, and I am one who really likes a clean view, I have very little problem with the front mounting as I really can't see the tube. But my main reason to report here is to serve the hobby, rather than just my own tank.

PS just checking my tank, and see that my spray bar would not fit on the back, it is too long. Would have to make another one, just when I thought I was done making prototypes...


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## Wookii (28 Jun 2022)

Interesting concept - this harks back to the CO2 diffusion systems that first came out when CO2 started to become commercially available for aquarium use. My first Dennerle CO2 diffuser that I bought some 20-25 years ago was essentially an inverted clear plastic try with a CO2 inlet pipe on the top - the tray was positioned with suckers on the glass just above the filter outlet. The tray would slowly fill with gas, and the water movement underneath it would diffuse that gas into the water column.

They then moved onto the various bubble track type diffusors to increase contact time (though I think they were more popular simply because people like to watch the bubbles travelling up) - amazingly Dennerle appear to still sell them!


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## Yugang (28 Jun 2022)

I just built prototype V.5, after some gentle pressure from @Hanuman . As I mount it on the back, it can't be full tank length as I have some limitations with hardscape.

After   giving my plants a very hard time while playing with CO2 levels     I was just for one week stabilising the tank at a 1.4 pH drop. I hope this shortened V.5 CO2 Spray Bar, positioned in a less optimal position for CO2 absorption will get me to that same level otherwise my plants get still another challenge.


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## Hanuman (28 Jun 2022)

Yugang said:


> I just built prototype V.5, after some gentle pressure from @Hanuman .


dammmm you sound like my wife that told me the other day that I forced her not to take her 3rd covid vaccin shot 😂. Despite me being very skectical about this vaccin and having shared that with her, I couldn't believe I was being branded an authoritarian dictator... Since then she realized the madness of her words... well I think she did... I'll check tonight again to make sure 😂


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## Yugang (29 Jun 2022)

I am now running a new CO2 Spray Bar, on the back just under the water spray bar. This one is  only 80% of tank length, due to limitations with the hardscape. 

I tuned it with the end button rotation at pH 1.1 drop, slightly below its maximum capacity.

After coming from 1.4 my plants won't be happy with another pH 0.3 adjustment, which corresponds to about 50% CO2 ppm change. I will now settle for the long term at 1.1 pH drop and will hopefully be forgiven for the inconvenience I caused. 

pH 1.1 compared to my old 1.4  is more comfortable for livestock, reduces CO2 consumption and is faster  to stabilise.

Below the FTS, it looks indeed a bit cleaner than the mounting on the front.


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## Yugang (3 Aug 2022)

My focus over the past weeks has been to optimize long term CO2 stability, day-to-day and week-to-week.

With the CO2 spray bar on the front of the tank (as per my first postings) CO2  stability is really good, both short term and long term. Yet after mounting on the back I experienced a slow long term drift of pH, about 0.1-0.2 over several weeks.

With the CO2 spray bar mounted on the back, below the water spray bar, it is impacted by changes in the water flow -- as plants on the back of the tank grow towards the surface:





The solution with improved performance is to position the CO2 Spray Bar in front and slightly above the water spray bar:





The most relevant parts of the water flow (around CO2 Spray Bar and surface agitation) are now virtually independent of the planting and flow lower in the tank, and I find long term stability within a couple of hundredths on the pH scale.

With only 80 cm of CO2 Spray bar in my 200l tank the pH will drop 1.5, with my current setting of the overflow (see below).

A full tank shot, the CO2 Spray bar is hardly visible (slightly above the water spray bar).





Building the CO2 Spray Bar is now a bit more work, but with the experience of nearly 10 proto types I manage within one hour and just a few GBP materials expenses.





For the finetuning of the pH drop (i.e. size of the CO2 reservoir) I do not longer rotate the end piece (it is now fixed with a screw), but prefer to exchange end pieces that each have a hole drilled in slightly different positions. The picture shows my favourite (1.5 pH drop), with the CO2 meniscus visible in the overflow.





Yesterday I celebrated a milestone, bought a bunch of new plants that will not anymore be mistreated with CO2 experiments. Will farm these plants and try a nice and healthy tank again. I hope that my experiments, and final solution will be helpful for others in the future. 

I will not go back to a reactor again, let alone diffusers, the CO2 Spray Bar is simple and is    the best solution I have had over the years.


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## Wookii (3 Aug 2022)

Interesting idea, but what about surface agitation? I always angle my spray bars up so the outflow hits the surface - I'd consider this essential to get enough surface agitation and sufficient surface gas exchange, With the CO2 diffuser placed there it looks like it will kill any potential surface movement?


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## Hanuman (3 Aug 2022)

Wookii said:


> Interesting idea, but what about surface agitation? I always angle my spray bars up so the outflow hits the surface - I'd consider this essential to get enough surface agitation and and sufficient surface gas exchange, With the CO2 diffuser placed there it looks like it will kill any potential surface movement?


Look to the right of the tank


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## Yugang (3 Aug 2022)

Wookii said:


> Interesting idea, but what about surface agitation? I always angle my spray bars up so the outflow hits the surface - I'd consider this essential to get enough surface agitation and and sufficient surface gas exchange, With the CO2 diffuser placed there it looks like it will kill any potential surface movement?


You may still direct the spraybar upwards, and just position the CO2 spray bar a little higher as well. I usually direct my water spraybar parallel to the surface, which gives enough agitation.


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## Yugang (3 Aug 2022)

Hanuman said:


> Look to the right of the tank


On the right 20 cm I don't have spray bar, as I have wood over there.


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## Hanuman (3 Aug 2022)

Isn't that a wave maker?


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## Wookii (3 Aug 2022)

Hanuman said:


> Isn't that a wave maker?
> View attachment 191915



Yes, a gyre by the looks of it - I'm guessing that's just for use at night or something, as it would defeat the purpose of the spray bar configuration otherwise.


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## Aleman (3 Aug 2022)

Hmmm, I'm liking this, and as it so happens I have a piece of 32mm Polycarbonate tubing that I could 'sacrifice' in the interests of science ... Just need some 32mm polycarb or acrylic end caps ...


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## Yugang (3 Aug 2022)

Hanuman said:


> Isn't that a wave maker?
> View attachment 191915


Yes I bought that one when I used a different set up, with a spray bar on the right. Now, with spraybar on the back I don't really need it anymore, but let it spin for 2 min every hour to give the water a bit of a mix and the fish some fun. I find a flow from the back to the front most friendly to stem plants that don't have to bend from left to right, as well as for the fish.


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## Aleman (4 Aug 2022)

Hmmm, thinking about this a bit more. Just how do you make 2 straight 90cm cuts in polycarbonate tube without it cracking, splitting or melting? I have a Dremel, with cutting wheel ... would melt and gum up, diamond wheel ... same, Circular saw .... err just no, Recip saw ... not a frickin' chance! Multi-tool ... vibrating with a fine blade on slow speed, and take it slowly ... Possible ???


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## Yugang (4 Aug 2022)

Aleman said:


> Hmmm, thinking about this a bit more. Just how do you make 2 straight 90cm cuts in polycarbonate tube without it cracking, splitting or melting? I have a Dremel, with cutting wheel ... would melt and gum up, diamond wheel ... same, Circular saw .... err just no, Recip saw ... not a frickin' chance! Multi-tool ... vibrating with a fine blade on slow speed, and take it slowly ... Possible ???



This is what I make, 1 inch pipe cut at 180 degrees (recently I prefer 220 degrees to contain the CO2 in a strong flow from the water spray bar). The ends are fully closed, so that the end pieces can be mounted without glue and the tube rotated in the end pieces for alignment.






Drawing straight lines over the full length. I use an aluminium 90 deg profile to hold the tube, and permanent marker:





Then carefully cut with a hand saw. The blade is held nearly parallel to the tube's surface:


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## Aleman (4 Aug 2022)

Yugang said:


> Then carefully cut with a hand saw. The blade is held nearly parallel to the tube's surface:
> 
> View attachment 191975


The one tool I don't have  Oh well, I guess you can never have too many tools  
Your design, was pretty much exactly what I was thinking it would be ... I may make a few alterations to fit in with my tank.
.
.
.
.
.
Japanese dozuki pull saw on way


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## Yugang (4 Aug 2022)

Aleman said:


> The one tool I don't have  Oh well, I guess you can never have too many tools
> Your design, was pretty much exactly what I was thinking it would be ... I may make a few alterations to fit in with my tank.
> .
> .
> ...


If you have questions about the details of the design, always here to help.

Please note that I never use glue, and that by varioius rotation options in the design we are very flexible to experiment with different positions for the CO2 Spray Bar relative to the water spray bar. If this is not clear from the pictures, happy to elaborate.

The most important alignment is that the CO2 Spray Bar is always horizontal. I usually position the top of the CO2 Spray Bar exactly at the tank water surface. When I want to mount it lower, I use a turkey blaster to blow a few bubbles of air in (as in a level tool), and with these bubbles it is also really easy to find the horizontal position.

After maintenance and water change, I usually use a turkey blaster to suck any air from the CO2 Spray Bar. As I illustrated earlier it will purge air automatically, but it is just a bit quicker next morning if an empty bar gets filled with pure CO2 without the need for air purging.


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## Aleman (4 Aug 2022)

What I love about this design is that it is so simple, which means it's elegant. I'm still trying to solve a lack of flow issue in the tank, due to hardscape,  which the spray bar and CO2 spray bar might go some way to solving ... I may also add a small cross flow pump on one end to make sure that there is sufficient flow where needed.

Oddly enough my real question is about the spray bar. I'm still playing around with the number, diameter and pattern of holes. in order to achieve "constant" (or consistent) flow along the length of the bar. Equal Spacing and equal diameter holes along the bar leads to high flow closest to the filter and low flow at the other end. Unequal distribution of the same diameter holes, more, closer together at far end gives the appearance of a consistent water flow. I suspect that smaller holes at the near end and bigger holes at the far end with an equal spacing between would give a similar flow. 

This is "obviously"  linked to pressure drop along the length of the spray bar. I guess just turning the flow of the filter up will solve my problem, and I can go with larger holes equally spaced.

Of course I could simply be overthinking the whole thing  ... and lets not talk about the floating plants that are going to hate being in a jaccuzzi ... Get rid and turn the light intensity down


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## Yugang (5 Aug 2022)

Aleman said:


> I'm still trying to solve a lack of flow issue in the tank, due to hardscape, which the spray bar and CO2 spray bar might go some way to solving ...


For the CO2 Spray Bar to work well, we need a decent flow. For the full tank stability, where surface agitation is key, flow is even more important (whether a diffuser, reactor or CO2 Spray Bar is used). With the water spray bar over the full back of the tank, driven by a powerful enough (filter) pump most layouts will have a good surface agitation as well as flow within the tank. I would therefore prioritize the flow from the water spray bar, rather than wave makers in the tank.



Aleman said:


> I'm still playing around with the number, diameter and pattern of holes.


That's also what I do, as I tried but find it hard to theorise what is the best design of holes in the water spray bar. To keep things simple, I calculate the sum of the surface areas of all my holes, and want that to be similar as the crosss section surface area of my filter hose. Then I play with the spacing between holes and see what happens.

When I first tested my latest design (CO2 Spray Bar mounted in front of water spray bar), I was worried about blowing CO2 bubbles out, and chose only 2 cm spacing of holes on my water spray bar. It worked, but it gave me too little surface agitation for my taste, so I went back to the 3 cm spacing that I most often use. This works fine for CO2 Spray bar and some decent flow in the tank (around 5 cm/ sec).


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## Yugang (6 Aug 2022)

*My current insights on CO2 stability**, short term (within the day) as well as long term (day-to-day, week-to-week) using the CO2 Spray Bar in different modes of operation*.

Three alternative approaches to using the CO2 Spray Bar:

*‘Overflow mode’*. We inject slightly more (5%) CO2 in the CO2 Spray Bar than the CO2 absorption into the water. The CO2 reservoir remains always full, and every few minutes we see an excess CO2 bubble escape from the CO2 overflow.
*‘Regulator mode’*. We use the CO2 Spray Bar below its capacity, so that the CO2 meniscus never reaches the overflow and no CO2 bubbles escape from the overflow. It is now the setting of the CO2 regulator that drives how much CO2 is absorbed in the tank.
*‘CO2/pH controller mode’*. As Regulator Mode, no bubbles escaping from overflow, but rather than the regulator it is the CO2/pH controller that drives the CO2 injection rate.

*Some general remarks on CO2 stability in tank (no CO2/pH controller)*

CO2 ppm stabilises when CO2 injection = CO2 surface outgassing + plant CO2 uptake. For a good CO2 stabilisation in the tank it is essential that CO2 outgassing and CO2 injection are both high enough. This follows from simple math, mentioned in several other posts, and will not elaborate again here. Irrespective of the injection method (diffuser, reactor, CO2 Spray Bar), a *good CO2 stability can only be achieved with good surface agitation *(gas exchange), and avoiding any changes in the surface agitation. *Changes of the flow pattern and surface agitation (e.g. adjust spray bar or lily pipe) have a significant impact on the tank CO2 ppm and stability*.
For tanks with good surface agitation, a requirement for good stability, both injection and outgassing will usually be much higher than the plant CO2 uptake. Changes in plant mass, growth or pruning, do change plant CO2 uptake, but this is likely to be minor as compared to total CO2 injection and outgassing. With tank maintenance and heavy pruning, the change in waterflow may outweigh the impact of removing plant mass. *Unless pH is precisely monitored with a probe, adjusting CO2 injection for plant mass may very well be counterproductive for CO2 stability*.


*1. ‘Overflow Mode’*

As the meniscus of CO2 will align itself with the overflow, the CO2-water absorption area will be constant. With the CO2 Spray Bar mounted in front, and in the flow of the water spray bar the flow at the absorption interface is stabilised as well unless the filter clogs up.

*The quality and stability of the CO2 regulator is no longer important*, as long as it injects enough. I usually set it so that I see a bubble of CO2 escape from the overflow every few minutes, and then don’t worry any more. *Monitoring flow rate and using a bubble counter is no longer needed,* just watch the overflow in action and if it ‘runs dry’ increase the injection a bit.

I use different overflow end pieces, with the hole drilled in different positions to adjust the CO2 reservoir capacity to my liking. This works better than the rotation that I used to do, as it is important to rule out unwanted changes in the position of the overflow.

For *levelling the CO2 Spray Bar horizontally, so that geometry is reproducible*, I use the tank water surface as a reference, or alternatively a few bubbles of air or CO2 in the nearly empty spray bar.

*The main factor that will drive both short term and long term CO2 stability are the surface agitation / gas exchange.


2. ‘Regulator Mode’*

We set the overflow so that under normal operation the CO2 meniscus will never reach it, and no CO2 will escape from the overflow. The system will then stabilise when CO2 absorption = CO2 injection from the regulator, and we have a *very similar function as with a traditional inline reactor. *

Now, of course, we need a good quality CO2 regulator that is both short term stable, and has no long term (day-to-day and week-to-week) drift. we need to use a bubble counter to regularly monitor & finetune the injection rate

While the CO2 Spray Bar functions mostly as in inline reactor, it *eliminates most of the traditional reactor’s challenges*. No noise. No flow reduction for filter. No safety concern when a cylinder blow out or regulator malfunction causes too much CO2 injection. No CO2 mist in tank.

*The main factor that will drive both short term and long term CO2 stability are surface agitation / gas exchange, as well as instabilities and drift from the CO2 regulator.


3. ‘CO2/pH controller mode’*

As with Regulator Mode, but instead using a CO2/pH controller to stabilise pH within a given bandwidth.

While the CO2 Spray Bar functions similar to an inline reactor, as per above, it eliminates most of the traditional reactor’s challenges. No noise. No flow reduction for filter. No CO2 mist in tank.

With a proper setting of the overflow, it can be used to fully maintain the function of a correctly working pH controller, while *mitigating risks sometimes associated with the CO2/pH controller.* When the controller injects more than a safe level of CO2 (malfunction, probe or KH change) the CO2 overflow will act as a safety valve and limit the maximum CO2 that the Spray Bar can inject.

*The main factors that will drive CO2 stability are the KH stability, calibration of pH probe, and upper/lower limits pH setting.*


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## Hufsa (18 Oct 2022)

Hi @Yugang , Im posting my questions here in this thread because I think it makes the most sense, but let me know if you want me to start a separate thread 😊
My current reactor (Yidao) is struggling *a lot* to keep up with my injection rate/surface agitation/flow combo, and as we have already discussed a bit earlier I want to try the CO2 spray bar on my system to see if it is a good fit for me.



Yugang said:


> Design rules / estimation
> For my tank (100 * 45 * 60 cm) I use a 1 inch, 90 cm long CO2 spray bar This is 216 cm2 surface area. The ratio between tank surface area (4500 cm2) and CO2 spray bar (216) is 20.8 :1. For other tank dimensions, this ratio is a good approximation how to find the optimal dimensions of the spray bar.



Im hoping you may be willing to provide a little bit of "hand holding"? Because of my chronic illness my working memory is affected and particularly these days doing mathematical calculations is especially difficult.
If youre willing could you help me make the determination for what size diameter and length of bar I need on my tank?
My tank is 100cm long and 50cm wide. I have PVC pipes in a variety of diameters already that I can use for the CO2 spray bar itself.
I would prefer if the CO2 spray bar was about 80cm long or a little less, longer than this and it might start to conflict with the pipes on the left and right side of the tank.
To refresh I have one water spray bar along the top of the tank's back wall, and (rather unusually) one bottom spray bar on the substrate that sends water up along the back glass pane.
I am thinking of mounting the CO2 spray bar directly below the top water spray bar, I dont think the current from the bottom water spray bar is strong enough to cause issues with the CO2 meniscus, and I wonder if it might actually be a benefit as the water movement up the back wall is much more stable with this setup than on a tank with no bottom spray bar and increasingly thick masses of plants at the back. Let me know if you require pictures of this setup.

I was thinking to aim the calculations on the CO2 spray bar a little high (maybe 1.2-1.4 drop?) and then adjusting down to 1.0 drop using one of your holes in the end cap. Do you still use 5mm?
Just to avoid the issue of making a CO2 spray bar that is under capacity, and needing to make a second bar.
Unfortunately PVC pipes are more expensive to acquire here, I wish we had your material costs.
I will try out with a grey PVC pipe first that is spray painted black, and then if I am happy with how it works on my setup I can buy an (expensive) black PVC bar and recreate the CO2 spray bar with the same measurements.


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## Hufsa (18 Oct 2022)

I just realised I could treat the surface area of half a spray bar as a flat plane, so it would just be a matter of taking the inner diameter x length of the bar 
I had somehow imagined the calculation to involve pi, calculating the volume of half a cylinder, quantum mathematics, one trampoline and two sacrificial goats and my brain just went "nope"


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## Yugang (18 Oct 2022)

Hufsa said:


> Hi @Yugang , Im posting my questions here in this thread because I think it makes the most sense, but let me know if you want me to start a separate thread 😊
> My current reactor (Yidao) is struggling *a lot* to keep up with my injection rate/surface agitation/flow combo, and as we have already discussed a bit earlier I want to try the CO2 spray bar on my system to see if it is a good fit for me.
> 
> 
> ...


Great to see you make this move @Hufsa , and happy to help with as much info and help as you may need 



Hufsa said:


> My tank is 100cm long and 50cm wide.


Mine is nearly same size, 100 * 45 cm, so that makes it easy to copy my setup to your tank. My CO2 Spray Bar is 80 cm long, and made of a pipe with 1 inch diameter (2*radius). The tank's CO2 need obviously depends on certain variables, mostly surface agitation, but the important reference point is that my CO2 Spray Bar gives about 1.5 pH drop when at full capacity (that is, the meniscus is 1 inch, 2.4 cm wide and 80 cm long ).

My recommendation therefore would be to use a 1 inch diameter pipe, so that your bar is not the limiting factor and you don't need to cut a second one. If you like to lower the capacity later you can test different end pieces with holes drilled in different positions to play with the meniscus.



Hufsa said:


> I am thinking of mounting the CO2 spray bar directly below the top water spray bar, I dont think the current from the bottom water spray bar is strong enough to cause issues with the CO2 meniscus, and I wonder if it might actually be a benefit as the water movement up the back wall is much more stable with this setup than on a tank with no bottom spray bar and increasingly thick masses of plants at the back.


I believe this set up would work really well. I would not worry about the flow of the bottom water spray bar disturbing the CO2 meniscus, you would need a huge flow to blow CO2 out from the pipe. Your setup also makes the mounting of the CO2 Spray Bar easier than in my setup, as I needed to find a way to attach my CO2 Spray bar to my water spray bar.

From your journal I know that you have some issues with your tank recently, and I imagine you don't want to add additional challenges playing with your CO2 ppm. I believe the smart way would be to not touch your CO2 regulator and bubble counter, and to just bring your CO2 tubing from your Yidao reactor to your newly installed CO2 Spray Bar. In that way your are sure that at least initially you are at same CO2 injection rate into the water, and normally the CO2 Spray Bar would work under its maximum capacity (it is now the regulator that sets the CO2 injection, not the CO2 overflow). When this works fine, you may start to slowly adjust CO2, either by adjusting your regulator or by using different end pieces with different hole positions (yes, I use 5 mm) to set the meniscus.



Hufsa said:


> Im hoping you may be willing to provide a little bit of "hand holding"?


More than happy, do let me know if you have any questions


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## Hufsa (18 Oct 2022)

Yugang said:


> (that is, the meniscus is 1 inch, 2.4 cm wide and 80 cm long )


1 inch pipe would be 25,4mm diameter, I figure I can use a metric 25mm pipe then?
So I gather your calculations are based on outer diameter? It doesnt matter really, I just wanted to use the same to keep things the most similar. Things are gonna be off by some milimeters here and there anyways and the final adjustment done by the 5mm hole in one end piece.



Yugang said:


> My recommendation therefore would be to use a 1 inch diameter pipe, so that your bar is not the limiting factor and you don't need to cut a second one.


Great  I will check "my stash" tomorrow to see if I have end pieces for 25mm pipe, if not it makes a good(/dangerous) excuse to go to the pet store again 😅


Yugang said:


> If you like to lower the capacity later you can test different end pieces with holes drilled in different positions to play with the meniscus.


Fairly sure I will need to do this, but having it adjustable like that is just a bonus not a drawback of the bar.


Yugang said:


> I believe this set up would work really well.


I hope so!


Yugang said:


> From your journal I know that you have some issues with your tank recently, and I imagine you don't want to add additional challenges playing with your CO2 ppm.


Honestly right now my CO2 injection is relatively high but not stable, Ive been measuring it over the past days using my new ph pen and it looks like the reactor is having trouble stabilizing itself after I changed the skimmer to run only at night. So there is already unstable levels during the photoperiod and a ton of BBA. Making the switch makes me nervous of course, but its possible that this will bring stability to the tank quicker than other options would have.



Yugang said:


> I believe the smart way would be to not touch your CO2 regulator and bubble counter, and to just bring your CO2 tubing from your Yidao reactor to your newly installed CO2 Spray Bar. In that way your are sure that at least initially you are at same CO2 injection rate into the water, and normally the CO2 Spray Bar would work under its maximum capacity (it is now the regulator that sets the CO2 injection, not the CO2 overflow). When this works fine, you may start to slowly adjust CO2, either by adjusting your regulator or by using different end pieces with different hole positions (yes, I use 5 mm) to set the meniscus.


I can try, but the injection rate right now is ridiculous because ive been trying to get it dialed in again and failing. So if theres a ton of gas escaping from the bar then I will probably tune it down relatively soon.



Yugang said:


> More than happy, do let me know if you have any questions


Will do 😊


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## Yugang (19 Oct 2022)

Hufsa said:


> 1 inch pipe would be 25,4mm diameter, I figure I can use a metric 25mm pipe then?
> So I gather your calculations are based on outer diameter? It doesnt matter really, I just wanted to use the same to keep things the most similar. Things are gonna be off by some milimeters here and there anyways and the final adjustment done by the 5mm hole in one end piece.


Yes, 25 mm should be fine and I would expect that to give you around 1.5 pH drop maximum. If you, at least initially, continue to use your regulator in its current settings then the hole in the end piece will not really make a difference.
(I currently use my pH/CO2 controller again, and then the overflow is only acting as a safety valve if anything goes wrong.)



Hufsa said:


> Fairly sure I will need to do this, but having it adjustable like that is just a bonus not a drawback of the bar.


It is so easy to drill a hole in an end piece. I now have a couple of end pieces that I can interchange. I prefer that over rotating my end piece, as I described earlier in this thread, as I need to worry less about reproducibility.



Hufsa said:


> the injection rate right now is ridiculous because ive been trying to get it dialed in again and failing. So if theres a ton of gas escaping from the bar then I will probably tune it down relatively soon.


The spray bar gives always 100% dissolved gas (unless bubbles escape from overflow), so there is no risk for any mist to appear in the tank. What you may do is to start with a 5 mm hole drilled in the centre, as you see in my current setup below, this will give a meniscus that is nearly at maximum and I would estimate a pH frop around 1.5. Obviously plants react better to increased CO2 ppm than to decreased CO2, so if your fish are OK this could be a good way to go initially.

EDIT: I realise that @Hufsa tank surface is 10% more than mine, which will give higher outgassing. When I mentioned pH drop estimation of 1.5, this was based on my own tank dimensions and should be corrected for the increased outgassing in @Hufsa tank. On the other hand, in my tank the pH drop is actually slightly above 1.5, closer to 1.6 (which means 25% more CO2 ppm than 1.5 equivalent). In summary, if I remember correctly @Hufsa  targeting usually 1.0-1.2, a one inch spray bar is most likely enough to do the job. With progressively more users with CO2 Spray Bar, we will get better statistics as to the best dimensions for any tank size.


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## DuyHung (7 Nov 2022)

Does it work for 24/7 Co2?  I hate the reactor noise so maybe try this one. Thanks for idea 🥰


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## sparkyweasel (7 Nov 2022)

Hufsa said:


> o involve pi, calculating the volume of half a cylinder, quantum mathematics, one trampoline and two sacrificial goats


No need, it can be performed with a simple incantation, three small bits of wood and 4cc of mouse blood.


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## Yugang (7 Nov 2022)

DuyHung said:


> Does it work for 24/7


No problem, you can have your _(spray)_ bar open 24/7 🍻🎊🎶

_(So no problem for CO2 Spray Bar or injection, but most hobbyist use CO2 only before/in photoperiod, say 12 hours -reduce CO2 consumption and more comfort for lifestock during night when O2 is low)_


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## DuyHung (8 Nov 2022)

Actually, my electric coil has broken 🤣 so I open 24/7 co2. Since I have tried this method, my PH drop 1.5 I think its ok but my dropcheck seem not chage so much. Its still green but I aim to yellow because I want OP co2. Btw I have a ques. Where should be the Co2 spraybar compair to water surface and water spraybar ? Rightnow, I place water spraybar directly equal surface and the co2 is below a little.
Thanks for help. I well note with this method I have no more noise compair to reactor 😃


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## Yugang (8 Nov 2022)

DuyHung said:


> Where should be the Co2 spraybar compair to water surface and water spraybar ?


I set it up as you can see earlier in the thread, my CO2 Spray Bar is at the water surface and the water spray bar just below:




@Hufsa has the CO2 Spray Bar just below the water spray bar, but she has a second water spray bar that creates a flow from bottom to top at the back of the tank and is making sure the CO2 Spray Bar gets enough flow:




It is important that the water spray bar always gives the same surface agitation, so that CO2 outgassing is constant. Furthermore, there should be a good flow of water around the CO2 Spray Bar. For the rest, there are many ways to make it work, including placing the CO2 Spray Bar at the front of the tank as I did initially.


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