# DIY Rex Griggs Reactor



## Barbara Turner (14 Mar 2019)

Hi All
Has anyone built one or found a good set of instructions?
Are there any sizing calculations based I'm guessing on flow rate or is it simply the bigger the more efficient?
Are there any good websites to buy the parts from?


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## foxfish (14 Mar 2019)

You might not find much choice with the size, standard water treatment vessel is either 10” or 20”.
The 20” are quite expensive and the 10” only work on pretty small tanks.
Having said that I am not actually up to speed on what is available,  some guys are useing different types of vessels but they are not clear so you can’t see how they are working.
@Zeus. has made  good reactors that have proven to work.
I have had great success useing a 12” clear water treatment vessel but I don’t think you can find them nowadays....
There is a link in my signature showing how to build one but that design does not seem to work so well with the standard 10” vessel.


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## X3NiTH (14 Mar 2019)

I'm using a 20" clear housing, plumbed in reverse with a 40mm diameter down tube.














Osmio 4.5 x 20 Inch Full Flow Clear Housing (I managed to get mine for half that price, but that was a few years ago though)

Depending on how you want to plumb it externally you can find the connectors here, the plumbing connections to the housing needed big o-rings to seal them because they leaked a constant drip (PTFE tape wasn't enough) for which I sourced a few appropriately sized vacuum cleaner roller bands from a spares shop (unusual yes but worked perfectly for a watertight seal).

I got the Eheim taps from Charterhouse Aquatics and the sponges from All Pond Solutions (pre filter sponges).

Certainly not cheap but it's robust and efficient, mines fed by a Qanvee inline atomiser on the outlet of my filter, it's totally silent in operation.


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## Maxplantinstitute (14 Mar 2019)

I built my cerges for about 50 £ using a 10" housing. My tank is 200l and the reactor works just fine without any foam to stop bubbles.  Add this and it could probably handle a 350-400l tank.


The hardest part was finding a riser tube that had the right diameter.
 Try to find parts that don't restrict flow and use as few elbows as possible.
This guy on YouTube has apparently made a vortex current version.  this is the only one i have seen so i am not sure if it was a success.


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## X3NiTH (14 Mar 2019)

Maxplantinstitute said:


> This guy on YouTube...........



Was the first person to reply to this thread!


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## Maxplantinstitute (14 Mar 2019)

X3NiTH said:


> Was the first person to reply to this thread!


 I guess It's a small interwebb, at least the planted corner of it.
How did that vortex work out for ya...


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## foxfish (14 Mar 2019)

Well vortex designs are my favourite to work with, I have made many versions but not for a few years now.
However my base model, made from a 12” vessel is still working as well as any reactor I have seen or read about, so I have not bothered to try and improve on it.
Vid in my signature of it working if you want to see it.


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## X3NiTH (14 Mar 2019)

I'm down to one sponge and 90% efficiency. I had 100% efficiency when I had a six foot coil of hose between the atomiser and the reactor (constant flow of water against bubbles that always want to float to the top), I removed the coil as I wanted more space so I have a little lemonade in the tank (it's only a 30L tank but it's powered by an Eheim 250T with the taps fully open and feeds a spray bar, my hourly turnover is beyond 10x). I'm on a CO₂ controller so I don't bleed CO₂ in slowly, it's dialled in to give a quick response so that I get a 1.6pH drop in about an hour.


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## Zeus. (14 Mar 2019)

Mine work well but use about 6Kg of CO2 a month on 500l tank pH drop of about 1.6pH. Hit target pH in about 30mins with twin injectors/solenoids/reactors which I control with pH controller and PLC - not cheap.
Thinking about adding a protein skimmer pump to help efficiency !


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## Barbara Turner (15 Mar 2019)

Thanks everyone for your advice

What about this? possibly make up two and fill one up with filter media and get rid of my canister filter completely. 

If I got the return pipe in the centre I could try and spin the water around it I'm just not sure if its going to make a big enough improvement to be worth the haedache trying to seal it. 

I'm also guessing I'm stuck with silicone sealant if I buy acylic tube or can you bond it onto PVC pipe fittings with solvent weld?


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## foxfish (16 Mar 2019)

If it was easy to get a feed pipe entering at a tangent , I think a lot more folk would do just that!
It is quite possible but you need the tools for the job.
The main problem is the massive variation from one setup to another ie ... the size of pipework, the power of the pump, the amount of C02 required.
So when someone asks .. will this work...  yes it might on some setups,  but not on others.
When I was experimenting over quite a few years, I had a three speed, high pressure pump.
With that and with numerous valves, I could offer many flow rates and add back pressure to see what setting worked best.
I think this is one reason  the big company’s are struggling to supply a single reactor to suit all needs .
A reactor powered by its own pump might be an answer ?
Anyway, it is great fun messing around with water, so I think you should try out any ideas you get....


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## Barbara Turner (16 Apr 2019)

Tested it today and worse than without..
Apart from a minor leaks that will be easy enough to fix it has a big problem.

The water co2 mix enters the top off centre, the inlet is forming a spinning vortex as planned.




 This vortex creates a low pressure area in the centre, this is pulling all the co2 into large bubbles  where they then travel down through the reactor in a double helix shape.
With the high flow rate through the reactor there nothing like buoyant enough to float back to the surface to be reitrained.
Sorry its really hard to photograph and my phone is going flat...  You can just about make out the helix of bubbles traveling through the reactor in the centre of this photo.





The next step is to try either baffles or some bio balls unless anyone has any suggestions?


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## foxfish (16 Apr 2019)

That sounds interesting, if I understand you are saying small bubbles are sticking together and forming a large bubble and that is being sucked down the eye of the vortex?.
I can’t really make much from those pictures....


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## Barbara Turner (16 Apr 2019)

I'm not sure if this will work but here's a video I've just uploaded on YouTube


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## foxfish (16 Apr 2019)

The problem is I can’t see how your design is working, where is the Co2 entering?
Where does the flow exit?


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## Barbara Turner (16 Apr 2019)

The water goes through a quavee co2 diffuser before entering the reactor, (I've taken it all apart now) 


Here is a clearer picture of the reactor(without the diffuser attached to the inlet) 


 
You can see the inlet at the top and exit at the bottom. The body is made from 100mm clear perspex x 600mn long
Heres a closeup of the inlet.


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## obsessed (16 Apr 2019)

HI
maybe the problem you will have is the tiny bubbles forced out of the quavee will gather back together and form a bigger bubble which in turn is kind of missing the point to reduce the bubble size with the reactor. forgive me if I've misread your post.  I've spent countless hours on this very subject and have tried a few different gadgets but after testing just the quavee on there own they were the better option for me and more economical on co2. Fox fish says it all. Fun trying new things
cheers


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## Barbara Turner (16 Apr 2019)

My water is reasonably hard so it's a challage to dissolve the co2 in,  I suspect at the minute your right and the quanvee is more efficiend flowing stright into the tank..


obsessed said:


> more economical on co2



The main reason isn't to save co2 (I use out of date fire extiguishers so it's not that expensive)
When My CO2 switches off half an hour before lights  out the tank so much clearer with out the microscopic bubbles floating arround.

I crunched some numbers and i'm not sure it's ever going to get this reactor to  work.

My pump is rated to 4000lph assuming this drops to 3000lph with filter / pipework etc..
3000lph =0.00083m³/s

Based on a 14mm inlet I have a inlet speed of 5.4m/s (12mph) , assuming I can slow this down with baffles / bioballs so its all flowing in the same direction in the body of the reactor (100mm pipe ) this speed will drops to 0.1m/s (10cm/s)
The problem is that googling bubble speed in water the example for a 6cm bubble only travel at 8cm/s smaller bubbles will be even slower. My water is traveling at 10cm/s..

The quanzee diffuser won't help as the larger bubbles will travel faster but I still don't think it will be fast enough...

Only thing I can think of is the bioballs will create enough turbulence that they will dissolve the co2 into the water  before  entering the tank..


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## Barbara Turner (16 Apr 2019)

Just thinking about it, if I put in an adjustable bypass loop missing out the reactor, I can slow the water down in the reactor and give the bubbles that don't dissolve chance to float back to the top.


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## obsessed (16 Apr 2019)

Eheim mech pro, filter media.its black plastic bits. could aid in the turbulance.


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## Citrix (17 Apr 2019)

This is one i build for my 50l tank, it handles 1-2BPS really well


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## Barbara Turner (17 Apr 2019)

Thanks looks good,
I'm guessing you have it setup vertically, do you run it with the bypass completely closed?

I'm just wondering if my theory is correct on getting the water speed through the reactor below 5cm/s  is correct, Do you know what the pipe diameter you have used and what the the flow rate you expect from your canister filter?


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## Citrix (17 Apr 2019)

Barbara Turner said:


> Thanks looks good,
> I'm guessing you have it setup vertically, do you run it with the bypass completely closed?
> 
> I'm just wondering if my theory is correct on getting the water speed through the reactor below 5cm/s  is correct, Do you know what the pipe diameter you have used and what the the flow rate you expect from your canister filter?


Well i made by pass to correct possible errors of pipe diameter and length of reactor. If i see bubles coming out, I open more bypass, if i start to hear bubble forming inside, i close more bypass.
I run it on eheim 1000l/h, but slow is much slower cause i also reduced pipes size to not have huge steel pipes on 50l tank.


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## Nigel95 (5 Dec 2020)

Any update @Barbara Turner?

I also have this co2 art / Qanvee atomizer and looking to use it with a reactor or external pre filter setup. This external filter was an interesting option but it seems that he fittings are only 12mm which will cut the flow a lot. The idea was My filter > atomizer > using EW 604 external canister (as a reactor)


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