• You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up
  • You can now follow UKAPS on Instagram.

Anybody use this Chinese External CO2 reactor?

ForestDave

Member
Joined
12 Nov 2020
Messages
292
Location
Forest of Dean
Two thoughts.
I'm keen to make one of these but as the clear pipe in the UK is not massively cheap, can you see any major issues with making it out of cheap bog-standard white or black pipe and just keeping an eye on the drop checker and bubbles or lack of bubbles entering the aquarium. (I understand it's much easier and more fun with the clear pipe).

Lastly, are the shop-bought CO2 reactors from say CO2 supermarket not worth buying, or do you guys just love making things and striving for perfection? (Not a bad reason, I love a DIY project myself but just wondered!)
 

Hanuman

Member
Joined
4 Jan 2019
Messages
1,427
Location
Thailand
I'm keen to make one of these but as the clear pipe in the UK is not massively cheap, can you see any major issues with making it out of cheap bog-standard white or black pipe and just keeping an eye on the drop checker and bubbles or lack of bubbles entering the aquarium. (I understand it's much easier and more fun with the clear pipe).
It's just a piece of pipe so technically anything will work, transparent, blue, white or black. The clear PVC has one major advantage. You can see what is happening and so give you some feedback on whether it's working right. That's why most people use the transparent PVC. But yes it's much more expensive than the standard colored PVC.

Lastly, are the shop-bought CO2 reactors from say CO2 supermarket not worth buying, or do you guys just love making things and striving for perfection? (Not a bad reason, I love a DIY project myself but just wondered!)
Yes and no. The reason rests on the fact that you can't use a one size fits all reactor. The bigger the tank, the bigger the reactors needs to be (either higher or wider). The proper functioning of a reactor depends on its capacity to slow water flow enough so that CO2 does not escape through the outflow.
If you go for a Rex Grigg I would suggest a 2inch diameter and ~24inch tall (at least 20inch). I made a 15inch tall reactor and retrospectively I realize I should have made it taller. I have a 160L tank.
 

ForestDave

Member
Joined
12 Nov 2020
Messages
292
Location
Forest of Dean
It's just a piece of pipe so technically anything will work, transparent, blue, white or black. The clear PVC has one major advantage. You can see what is happening and so give you some feedback on whether it's working right. That's why most people use the transparent PVC. But yes it's much more expensive than the standard colored PVC.


Yes and no. The reason rests on the fact that you can't use a one size fits all reactor. The bigger the tank, the bigger the reactors needs to be (either higher or wider). The proper functioning of a reactor depends on its capacity to slow water flow enough so that CO2 does not escape through the outflow.
If you go for a Rex Grigg I would suggest a 2inch diameter and ~24inch tall (at least 20inch). I made a 15inch tall reactor and retrospectively I realize I should have made it taller. I have a 160L tank.
Thanks Hanuman.
I'll probably wait a bit and get a clear pipe in that case. Cheers for the tip on the height, my tank is probably about 160L once filled with AS and rock.
Out of interest, do you think narrow and tall is better than wider and shorter as it may condense the bubbles into a tighter space?
 

Zeus.

Fertz Calc Meister
Joined
1 Oct 2016
Messages
4,604
Location
Yorkshire,UK
The proper functioning of a reactor depends on its capacity to slow water flow enough so that CO2 does not escape through the outflow

Plus the slower the water in the chamber the higher the pressure the better a Venturi works :thumbup:
 

Hanuman

Member
Joined
4 Jan 2019
Messages
1,427
Location
Thailand
Out of interest, do you think narrow and tall is better than wider and shorter as it may condense the bubbles into a tighter space?
It's all the same in my opinion. It's just a relation between flow and CO2 bubble buoyancy. You could technically make a 1/2inch diameter reactor but then you would probably need to make a 5 meter tall or more reactor - lol
My opinion is the Rex Grigg is suited for medium to smaller tanks as it has a small foot print. The Cerges is better for bigger tanks. If you search google you will see that people with bigger tanks tend to use a Cerges type reactor. It's actually easier to make as you buy a clear water filter housing. Some people use a 20inches tall Cerges reactor.

Also something to consider, it's technically better to have the CO2 reactor on its own loop rather in line with your canister. This allow constant flow in time. If you put it in line with the filter, flow will progressively slow down as the filter gets clogged which introduces variations in Co2 injection through time. Most people do it this way though (myself included) because it's easier but it's not ideal.

Some litterature:
Dual venturi DIY External CO2 reactor (last post on this thread is from me)
 
Last edited:

Hanuman

Member
Joined
4 Jan 2019
Messages
1,427
Location
Thailand
Plus the slower the water in the chamber the higher the pressure the better a Venturi works :thumbup:
Well I think the venturi operating properly has more to do with the low pressure induced in the venturi port itself due to the restriction rather than in the chamber. In other words the CO2 is not being pushed to the venturi port but rather being sucked by the venturi port.
 

Zeus.

Fertz Calc Meister
Joined
1 Oct 2016
Messages
4,604
Location
Yorkshire,UK
Well I think the venturi operating properly has more to do with the low pressure induced in the venturi port itself due to the restriction rather than in the chamber. In other words the CO2 is not being pushed to the venturi port but rather being sucked by the venturi port.

When we use a straw in a drink do we suck the water up or does atmospheric pressure push the water up the straw, the current accepted theory is atmospheric pressure pushes the water up. We just think we are sucking it up.
In a ventri system its the pressure difference between the chamber and the ventri outlet that creates a force which pushes the water/air to the ventri outlet. The bigger the difference in pressure the better a ventri works, so a wider chamber generates more pressure so works better.
 

Hanuman

Member
Joined
4 Jan 2019
Messages
1,427
Location
Thailand
When we use a straw in a drink do we suck the water up or does atmospheric pressure push the water up the straw, the current accepted theory is atmospheric pressure pushes the water up. We just think we are sucking it up.
In a ventri system its the pressure difference between the chamber and the ventri outlet that creates a force which pushes the water/air to the ventri outlet. The bigger the difference in pressure the better a ventri works, so a wider chamber generates more pressure so works better.
It's not the flow in the chamber/reactor which resides long after the venturi port that causes the venturi to work. It's the pressure differential between before the venturi port and the venturi port itself (the fitting adapter in my case). You could have no reactor/chamber after the restriction that the venturi would still work the same and there would still be low pressure and a vacuum created that would force fluid/CO2 through the venturi port. In fact you need a minimum amount of velocity going through the restriction for the venturi to work else it doesn't.
Screen Shot 2021-02-16 at 20.17.26.jpg


As for the "sucking" it is pretty much the terminology used with venturi injectors ;) but yes it's the difference in pressure that causes it.

images.jpeg
Venturi-jet.png


venturis-1.jpg
 

Zeus.

Fertz Calc Meister
Joined
1 Oct 2016
Messages
4,604
Location
Yorkshire,UK
It's not the flow in the chamber/reactor which resides long after the venturi port that causes the venturi to work. It's the pressure differential between before the venturi port and the venturi port itself (the fitting adapter in my case). You could have no reactor/chamber after the restriction that the venturi would still work the same and there would still be low pressure and a vacuum created that would force fluid/CO2 through the venturi port. In fact you need a minimum amount of velocity going through the restriction for the venturi to work else it doesn't.
View attachment 163046

As for the "sucking" it is pretty much the terminology used with venturi injectors ;) but yes it's the difference in pressure that causes it.

View attachment 163047View attachment 163049

View attachment 163048
Yes and No IMO, as if the pressure in the reactor chamber was less(or the same) than in the venturi port it would not work eg without flow (shut value at bottom of reactor), no flow no pressure difference. their is no pressure difference (aka suction) no venturi effect happens.

In a carburettor its the atmospheric pressure that pushes the fuel in, so IMO its the pressure in our CO2 reactor chamber that pushes the gas/water thought.
1613485570410.png


But yes 'suction' is a term used to described what what happens when their is a pressure difference.

Purley an academic debate :D, as long as it works
 

Franks

Member
Joined
26 Aug 2015
Messages
242
Simple question related to this.

Is there a Co2 reactor that is available to buy that works as intended and is far superior to using an in-tank or inline atomiser?

Thanks
 

Franks

Member
Joined
26 Aug 2015
Messages
242
Yeah I get all the principles and understand the definition, but 'works as intended' suggests it's not prohibitive to buy, won't leak, won't work, won't incur a negative such as a large reduction in filter flow.

Reading the reviews of most manufacturers efforts suggest most people just end up with a headache when trying to use a reactor. I guess there isn't an off the shelf solution then?
 

Hanuman

Member
Joined
4 Jan 2019
Messages
1,427
Location
Thailand
Actually I know many who don't have problems and are happy with their reactors but I suspect those people have medium to small tanks. Regarding flow, there is no way around that. Any reactor will inevitably reduce the overall flow. That is why among other reasons serious people in the hobby have the reactor in a separate loop from the canister.

There are off-the-shelf solutions, but as I stated above, one size does not fit all. That's simply because a reactor design is dependent on flow hence the reason why a large majority end up doing their own reactors. The best so far I have seen are those made by NilocG, but looking at their construction, anyone can do those at home.
 

Hanuman

Member
Joined
4 Jan 2019
Messages
1,427
Location
Thailand
Just found this tube connector. Would this work as a venturi or do you need the 1/4 CO2 pipe to stick out inside the larger pipe with the bevel facing away from the flow?
Sorry I missed this post. I don't think it will work as this is a simple T-Joint and the opening inside is most probably flush with the diameter of the main connecter. What will happen is that water will simply shoot out of the smaller 1/4'', which in fact is what this T-joint was designed for. If you look at my pictures above the smaller connector is protruding inside the bigger connector and the face is cut to a 60 degree angle facing off the water current. That's how you create the venturi effect. In youtube you can find many people doing this at larger scales for aquaponics/hydroponics etc.
 

zozo

Member
Joined
16 Apr 2015
Messages
8,314
Location
Netherlands
Although with second thoughts the fitting is the constriction so Yes it should work
Indeed it might... :) You can also DIY one that might do better. With this, I tested it a few years back as an air venturi and worked a charm.

Knipsel.JPG


You can drill a very small hole in the hexagonal nut say 1mm or even smaller if you want. Then what i yet have not tested but in theory, it should do even better. Drill this hole in an incline in the flow direction. Than take a larger drill in 4.2mm and drill a 5mm deep hole at 90° on top of the 1mm declined hole. The Hex nut has enough material to it for that. Tape M5 thread in this 4.2mm hole and screw in another 4mmxM5 hose pilar. I used one like this with a O-ring and a clamp nut.
p22466023.jpg

Or use one like this with a drop of Locktite or other sealant on the thread.
messing-slangpilaar-m5.jpg


And this goes again on the other end with a rubber washer.
PVC-U-23-Slangtule.jpg



It is 10mm internal diameter, which makes it 2mm reduction in a 16/12mm hose. :) And the 1mm inlet gives a finer bubble. :)
But as said I didn't test it with an inclined 1mm hole, I drilled it straight and it already worked well as a venturi inlet. Later I thought I should have tried to drill it inclined. with the flow direction. There was nothing to lose to do that anyway. (Well other than snapping a drill if you are not careful.)
 
Last edited:

ForestDave

Member
Joined
12 Nov 2020
Messages
292
Location
Forest of Dean
@Hanuman
Could you explain the purge valve please? Is that a simple ball valve adjusting the flow to the Venturi?
Also you have two other green valves and pipes going into the reactor, is that for fertiliser?
Thanks
Dave.
 

Attachments

  • 1613894496976.jpeg
    1613894496976.jpeg
    1.2 MB · Views: 61
Top