# External CO2 reactor or DIY



## chr15_8 (6 Feb 2021)

Hi all,

Wondering if anyone can recommend an external reactor?

If not I'm considering a DIY reactor using a external filter booster as the base APS have one for £15 with 16mm inlet and out let. The external filter booster is basicly an empty external filter.

Thanks
Chris


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## Zeus. (6 Feb 2021)

Not one that is any better than a DIY one, if your handy making a DIY one is pretty straight forward, The APS EF2 I did for my 500l are OK but think @Hanuman DIY reactor is much superior IMO and do plan to copy it soon


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## Hanuman (7 Feb 2021)

This principal can been seen in this video which is for O2 but same principle applies.


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## Zeus. (7 Feb 2021)

Hanuman said:


> This principal can been seen in this video which is for O2 but same principle applies.



Yes, seen that some time back and was the basis of the mod I did to my APS EF2





But never got it to work as well as in the video, think the angle of the funnel I used wasn't 'acute' enough


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## foxfish (7 Feb 2021)

That is  the same principle as the one I built years back in my signature link!


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## chr15_8 (7 Feb 2021)

Thanks all, some things to think about there!

I was going to suggest a diffuser located within the filter booster but you answered that question in one if the other threads. The super oxygen system looks interesting. Will need to see if I can find much on that! Will be an interesting DIY.

Thanks again


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## chr15_8 (14 Feb 2021)

Would there be any advantage or disadvantage by adding a diffuser into the DIY reactor? I'm thinking the smaller bubbles will diffuse easier but it would obviously be harder to clean.

Thanks Chris


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## Zeus. (14 Feb 2021)

chr15_8 said:


> Would there be any advantage or disadvantage by adding a diffuser into the DIY reactor? I'm thinking the smaller bubbles will diffuse easier but it would obviously be harder to clean.



Smaller bubbles diffuse CO2 into water faster due to the volume to surface area ratio (smaller the better), however smaller bubbles more likely to end up in tank as not as buoyant as bigger ones


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## Hanuman (15 Feb 2021)

chr15_8 said:


> Would there be any advantage or disadvantage by adding a diffuser into the DIY reactor? I'm thinking the smaller bubbles will diffuse easier but it would obviously be harder to clean.
> 
> Thanks Chris





Zeus. said:


> Smaller bubbles diffuse CO2 into water faster due to the volume to surface area ratio (smaller the better), however smaller bubbles more likely to end up in tank as not as buoyant as bigger ones


Exactly that. You do not want to have a diffuser either in the reactor or before. That defeats the purpose of a reactor. Small bubbles produced by a diffuser will inevitably go to the tank due to them being poorly buoyant. This is not just theory it's been tested and proven by yours truly. The fact is that when I installed the CO2 reactor I did not remove the inline diffuser in case something was to go wrong with the reactor. I did switch back to the diffuser temporarily for testing purpose. Well that reactor was absolutely useless when using a diffuser. All those tiny bubbles just passed through the reactor and ended up in the tank as if there was no reactor.


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## foxfish (15 Feb 2021)

Hi Hanuman, I don’t know if you have watched my video but I don’t have any bubbles escaping the reactor  even at 4500lph from a high pressure 90watt  pump and I do use an small diffuser.


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## Zeus. (15 Feb 2021)

foxfish said:


> I don’t know if you have watched my video but I don’t have any bubbles escaping the reactor even at 4500lph from a high pressure 90watt pump and I do use an small diffuser.



Think that was due to the great vortex you had in your setup, which was effectively trapping the bubbles in reactor. But I had a similar experience to @Hanuman with small bubbles, reducing the flow though the reactors did help reduce/stop small bubbles getting through, needed the 'Foxfish Vortex' IMO


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## X3NiTH (15 Feb 2021)

I wonder if anyone’s tried modifying a large conical fermenter to run upside down inline?





You get the idea.


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## Hanuman (15 Feb 2021)

foxfish said:


> Hi Hanuman, I don’t know if you have watched my video but I don’t have any bubbles escaping the reactor  even at 4500lph from a high pressure 90watt  pump and I do use an small diffuser.


Hi. Yes I have. Those bubbles from your diffuser are no where near the bubbles size from an inline diffuser which are very fine. In fact one can see rather large bubbles from your diffuser going straight up. I challenge you to adapt an inline diffuser before your reactor. I am pretty certain the bubbles will escape, at least partially.

edit: Bubbles from inline diffusers (at least from mine) produce bubbles that are so small that they can stay in suspension in the tank for quite sometime before escaping to the surface.


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## Hanuman (15 Feb 2021)

X3NiTH said:


> I wonder if anyone’s tried modifying a large conical fermenter to run upside down inline?
> 
> View attachment 162858
> 
> You get the idea.


I was actually recently looking at a way to replicate the cone from the video I posted above. You found it. Only issue is you cannot see what is happening but I suppose that's luxury.


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## X3NiTH (15 Feb 2021)

I occasionally have these eureka moments, only sticking point with this idea is the smallest I saw was 11Litres so that will be tough to hide under a tank, got a fish room? no problem!

I’ve got an in-line before my Cerges/Dwell 20”, zero bubbles out the spray bar totally silent, even with my co2 cranked as pH probe is cooked at the moment and haven’t changed it yet so the controller profile is just bananaing around and is just pouring gas in and not reaching the set profile to shut the solenoid, tanks pearling like mad and it’s not o2, co2 is nucleating out of solution from points on the leaf periphery, I’m probably in excess of about 50ppm in the tank, no fish mainly just Buce and bladder snails, using same type probe that last year killed 32 Rasbora Kubotai 2 days after bringing them home because it couldn’t hold a reading and acting just like this one is now, showing a climb in pH when it’s actually dropping, haven’t kept a freshwater fish since!


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## Zeus. (15 Feb 2021)

X3NiTH said:


> only sticking point with this idea is the smallest I saw was 11Litres so that will be tough to hide under a tank



and others no so cheap 😬


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## X3NiTH (15 Feb 2021)

Yeah the prices are brutal, no limits to perfection though!


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## Zeus. (15 Feb 2021)

FastFerment Conical Fermenter - Home-Brew Kit - BPA Free Food grade Primary Carb £65 not too bad


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## X3NiTH (15 Feb 2021)

Once you add all the sundries to get it working properly maybe looking at around £100. Need to ensure the lid is watertight for upside down use, you could silicone it shut I suppose but maintenance would be a nightmare.


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## Hanuman (15 Feb 2021)

X3NiTH said:


> I’ve got an in-line before my Cerges/Dwell 20”, zero bubbles


Yes at the end of the day it's all a relation between flow and gas buoyancy. I suppose I could also have no bubbles coming out of my Rex Grigg style reactor when using a diffuser but I would probably need to double the hight of the reactor OR increase the diameter OR create a bypass to slow water flow in the reactor.


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## Zeus. (15 Feb 2021)

Hanuman said:


> Yes at the end of the day it's all a relation between flow and gas buoyancy. I suppose I could also have no bubbles coming out of my Rex Grigg style reactor when using a diffuser but I would probably need to double the hight of the reactor OR increase the diameter OR create a bypass to slow water flow in the reactor.


Which is why I was always keen to make the reactor as wide as possible (like the APS EF2), having the bypass did help when I was testing with the CO2 ART inline atomisers, I had also provisional planed to make my 'next' CO2 reactor as wide as possible, double the radius of reactor chamber decreases the flow by Four. @X3NiTH conical fermenter is wide  - tank bulk connector on the top/screw lid ( which will be bottom when its a CO2 reactor), then just need to fit a CO2 outlet return for venturi


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## Hanuman (15 Feb 2021)

Zeus. said:


> Which is why I was always keen to make the reactor as wide as possible (like the APS EF2), having the bypass did help when I was testing with the CO2 ART inline atomisers, I had also provisional planed to make my 'next' CO2 reactor as wide as possible, double the radius of reactor chamber decreases the flow by Four. @X3NiTH conical fermenter is wide  - tank bulk connector on the top/screw lid ( which will be bottom when its a CO2 reactor), then just need to fit a CO2 outlet return for venturi


Both the Rex Grigg and Cerges reactor do the same. Reduce flow. One is higher and thiner. The other is shorter and wider. All for the same. This said a Cerges type reactor is probably more adapted for bigger tanks due to increased flow required. It would be impractical to have a very tall Rex Grigg reactor.


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## foxfish (15 Feb 2021)

I did try with an UP inline and with no diffuser as well, the best results were indeed with the course diffuser but all three worked on the lower flow ratings,
As Zeus pointed out... it is the perpetual vortex that continually mixes  and abradeds the bubbles against each other  and therefore breaking them down.
It is such a basic concept but surprisingly difficult  to get just right.


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## chr15_8 (6 Mar 2021)

A lot of usfull and good ideas to consider so thanks for that. 
I finally got round to making a quick and experimental reactor and plumbed in a few days ago. Not sure how it will work but there are currently no micro bubbles going through. Hopefully the picture explains but the water is acting as a vortex and is fairly rough where you can see the bubbles gathering at the top. I purged a fair amount of air out the tube so I know I have co2 entering the system which is why there is so much already gathered. Hoping in normal operation there won't be as much. When I first set it up I had about 2/3x the amount of air at the top which took about 2 hours to dissipate.

I have placed the drop checker close to the bottom as the instructions said. My only worry is the bromothymol blue is a few years old although never been opened so not sure if it goes 'off' 

Please excuse the mess! I need to tidy it all up still!


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## foxfish (7 Mar 2021)

One issue might be the right angle elbow will defiantly  cause loss of flow, that is why i came up with the internal bottle idea as it does not effect the  flow anywhere near as much as a right angle bend.
However if you are getting a good strong vortex, then that is great and should work well.
Where and how does the water exit?


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## chr15_8 (7 Mar 2021)

Well its not working too well to be honest. Turned the co2 off last night at 10pm and still have some in the reactor now. Was looking at your DIY reactor last night (first time coming across it 🙈) and now have the filter housing and hosetails ordered up. Have found a bottle that will hopefully be suitable also. Hopefully have it up and running come next weekend.


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