# Cerges Reactor w/ Venturi



## Mr.Shenanagins (20 Jul 2022)

For a while I have been using a needle wheel pump for my co2 diffusion and while it works well, I’m not convinced that just the mist is enough for my sumped setup, not to mention its unsightly. I have not been happy with my plant growth and have noticed some unsightly algae that I believe is due to an imbalance of CO2. I have since acquired a water filter housing to create a cerges style reactor. I will be following the typical setup, however, I’ve incorporated a Venturi line that feeds directly into my needle wheel. Once the bubble at the top reaches that point, the Venturi will suck in the undissolved CO2 and return it to the cerges as a mist that will continue to break down or be shot out. I will have the exit pointed right at my return pump. The Venturi and co2 line are both being fed into the top of the water filter, I drilled two small 3/16 holes and shoved the hoses through. I did it this way so I can see the co2 bubbles being injected as I don’t have a bubble counter (co2 hose isn’t inserted in this picture). I’ll advise my results once it gets going for a while 👍🏻


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## Yugang (21 Jul 2022)

It is a nice setup, perhaps the following link is helpful








						Dual venturi DIY External CO2 reactor
					

This unit cost about 20$ due to using Clear PVC housing, you can use solid 2" pipe if you wish.  You can find all the parts at any Orchard Supply Hardware or Home Depot.  Two: 2" slip to 1/2 threaded bushing  Two: threaded 90 elbow 1/2" barbed About 10 Bioballs if desired 12" of rigid...




					barrreport.com


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## Mr.Shenanagins (21 Jul 2022)

@Yugang Yes sir, Tom’s design is what inspired the addition of the Venturi. I believe he then abandoned the pvc setup to do what I did but I haven’t seen anything in the forums showing he updated it. I initially used his “internal” design but those are better for smaller setups.


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## Mr.Shenanagins (31 Jul 2022)

Whelp, turns out this reactor works really well. The Venturi for sure is assisting, however, it’s providing a light mist during the whole cycle. It’s currently about 3-4” down so I will need to push it down even further, OR, put an irrigation ball valve on it to keep the bubbles from getting sucked in too quickly early on.


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## foxfish (31 Jul 2022)

Did you try replacing the center tube with a  plastic bottle as in my version?


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## DeepMetropolis (31 Jul 2022)

Interesting, I've seen Tom's version of it. But I'm interested the noise of the pump and the hitting bubbles.. Tried it here but the aquamedic return pump started to make too much noise for my taste.


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## Mr.Shenanagins (31 Jul 2022)

foxfish said:


> Did you try replacing the center tube with a  plastic bottle as in my version?


No sir I haven’t tried the reverse water bottle method yet. At the moment the setup is handling my gas quite well but I could use less mist which is my own doing with the Venturi hose placement.


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## Mr.Shenanagins (31 Jul 2022)

DeepMetropolis said:


> Interesting, I've seen Tom's version of it. But I'm interested the noise of the pump and the hitting bubbles.. Tried it here but the aquamedic return pump started to make too much noise for my taste.


The noise level is minimal, the needle wheel pump handles the bubble rate just fine. I’d imagine the bigger the needle wheel the quieter it would be. This one only puts out 99gph and it’s handling my injection rate like a champ.


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## Mr.Shenanagins (1 Aug 2022)

foxfish said:


> Did you try replacing the center tube with a  plastic bottle as in my version?


What kind of bottle do you think would work best in your opinion?


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## Yugang (1 Aug 2022)

Mr.Shenanagins said:


> Whelp, turns out this reactor works really well. The Venturi for sure is assisting, however, it’s providing a light mist during the whole cycle.


I am intrigued how a reactor produces mist in the tank. It should not. Are you perhaps injecting fine bubbles / mist into the reactor (with your needle wheel pump)? If so, the buoyancy of these tiny bubbles could be too low, so that they go with the flow and escape from the exit without dissolving.

A  reactor works just fine if you inject large bubbles straight from the CO2 tubing ( 2-3 mm bubble diameter). These bubbles should dissolve in the reactor whithout producing any noticeable mist.


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## Mr.Shenanagins (1 Aug 2022)

@Yugang  Yes I agree with you, however a common issue with the cerges was a big co2 bubble starting to develop at the top. The Venturi idea was added to minimize that, so that when the co2 accumulation reached a certain point the Venturi would take on that extra co2 and produce a mist.


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## Yugang (2 Aug 2022)

Mr.Shenanagins said:


> @Yugang  Yes I agree with you, however a common issue with the cerges was a big co2 bubble starting to develop at the top. The Venturi idea was added to minimize that, so that when the co2 accumulation reached a certain point the Venturi would take on that extra co2 and produce a mist.


If a big CO2 bubble has formed in the top, re-injecting CO2 from that bubble back into in water intake will add close to nothing to the effciency of the reactor.

The best is to increase the water flow / CO2 injection ratio, so that the big bubble in the top of the reservoir does not develop in the first place. A too low water flow is really the root cause that needs to be addressed for the reactor to work well.


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## foxfish (2 Aug 2022)

I think the bottle size will be the result of trial and error but I found a rounded top rather that a long taper top worked best for me.


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## Yugang (3 Aug 2022)

Mr.Shenanagins said:


> I could use less mist


I am reading         Tom Barr's original post again     and (many years ago) he seemed to actually see the mist from the double venturi as a beneficial feature. Indeed some experts believe(d) that mist, besides fully dissolved CO2 is beneficial for the plants.

The best reactor IMO is the simplest,         as there is no need to make it more complicated than necessary, while introducing new and unnecesary problems that need to be solved.   So for those who like mist the double venturi can do just that, otherwise I really don't see the benefits and I would straight go to the simplest reactor design. A reactor does not need to be more complicated than a column with a water flow and bubbles.

Note: with CO2 mist in the tank the readings of drop checkers and pH probes become incomplete/meaningless, and it will be even more important to observe the fish wellbeing.


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## Mr.Shenanagins (3 Aug 2022)

foxfish said:


> I think the bottle size will be the result of trial and error but I found a rounded top rather that a long taper top worked best for me.





A bottle like this then?


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## Mr.Shenanagins (3 Aug 2022)

Yugang said:


> Note: with CO2 mist in the tank the readings of drop checkers and pH probes become incomplete/meaningless, and it will be even more important to observe the fish wellbeing.


I agree with you here, my DC did not work will with the misting. Now that I have my reactor setup it’s getting lime green. In terms of the misting I have to agree if the reactor is setup right you should get 100% dissolution without any mist.


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## Mr.Shenanagins (3 Sep 2022)

@foxfish The bottle trick is working nicely! I used a bottle similar to the one I posted above and today I came home to a lime/yellow DC. Bubble rate is pretty significant as I expected but working well and NO gas buildup at all. My pump is a reef octopus Aquatrance 1000S with a max output of 100gph and its plenty to handle this reactor thankfully. I’ll post it working when I can this week 👍🏻


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## foxfish (4 Sep 2022)

That is great, well done for carrying  on the experiment.


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