# External CO2 reactor



## B4M (20 Apr 2010)

I built this CO2 reactor about 4 months ago and it has been performing great. I can't take credit for the design as it is a combination of Ed and Beholds with a venturi loop from a design of Tom Barr's with only a few of my ideas. 

I wanted to give it some time to test prior to posting to confirm acrylic can be bonded to PVC and confirm the bleed valve holds. Given the time in use I'm now confident in both.

This was the assembled reactor:





Most of the parts were purchased from Henderson's plastics, ebay or online aquarium suppliers. 

Assuming it's of interest I'll put together a summary of how to make and along with list of parts needed.

Regards,

B4M


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## SKP1995 (20 Apr 2010)

It's definitely of interest to me, I was keeping an eye on Ed's reactor a while back.  How much do you reckon it hast cost to build in total?


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## B4M (21 Apr 2010)

Piemonster said:
			
		

> It's definitely of interest to me, I was keeping an eye on Ed's reactor a while back. How much do you reckon it hast cost to build in total?


Thanks for the interest I'll work out the cost.

So for parts I used the following:

From Hendersons Plastics






The following are from ebay. As ebay links have a habit of disappearing I've included the description and a search for this should find a similar auction.
50mm x 3mm Clear Acrylic Tube Plastic Pipe x 500mm Â£4.19 + Â£4.49 p&p
4mm Airline Connector Blue x2 Straight 99p + 47p p&p
Jubilee clips 10 pc 13-27mm Â£1.95 + Â£1.49 p&p

The following from Fantasea Aquatics





The white thin tube can be purchased in B&Q or Homebase: FFA Concept PVC Round Tube White (L)1000mm x (W)7mm x (T)1.25mm Â£2.80 You'll find it with the ironmongery along with steel & brass rods etc.

For the gluing the acrylic (otherwise known as perspex or PMMA) into the PVC sockets I did considerable research. 
I spoke to this crowd and they recommended the following: Polyweld THIN Â£2.99 + Â£1.50 p&p
However I found it to be very thin and it dryed almost instantly when brushed onto the tube. I ended up applying liberally then dripping a little more into the join. If I was buying again I'd try the medium version: Polyweld MEDIUM same price

I also used some araldite, ptfe tape, silicon and a short length of CO2 tubing.

So cost about Â£60 but p&p was a significant part. 

B4M


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## a1Matt (22 Apr 2010)

Nice looking reactor.
I also built a DIY external reactor with barr venturi loop - mine also cost about Â£60.


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## SKP1995 (23 Apr 2010)

Awesome, cheers for the comprehensive breakdown of what's needed, think I'll start gathering bits to make one soon.  Expect some posts regarding assembly when I do!


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## zig (23 Apr 2010)

Nice job, good writeup as well, similar to the ones that I make for myself except I usually use 40mm tubing.


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## chris1004 (24 Apr 2010)

Hi,

Â£60!!!!! 

I thought the DIY option was to save a bit of cash. My AM1000 cost less than that delivered.   

Regards, Chris.


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## B4M (24 Apr 2010)

chris1004 said:
			
		

> I thought the DIY option was to save a bit of cash. My AM1000 cost less than that delivered.



Fair point. But if you wanted to add a venturi loop you'd need to buy the extra fittings along with the AM1000. If you don't want the venturi these can be removed from mine and save a little. 

I liked the look of the Aquamas reactor if I was buying but that was â‚¬70 + â‚¬19.50 p&p from Germany. That would then still need the extra bits for the venturi. So when my wife asked I could say DIY was the cheaper option with a clear conscience.   

B4M


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## B4M (25 Apr 2010)

OK so here's a summary of how to make once you have all the parts:






First cut the acrylic tube to length. I cut to 350mm but you could get away with less. 
Now prepare for bonding into the PVC socket and elbow. I took the corner off the cut tube with a file and roughened the length that will engage into the socket a little using coarse sand paper. 
As mentioned previously the thin polyweld is very thin and drys fast so suggest using medium. I coated both surfaces with plenty then inserted tube until fully engaged. I brushed a little more at the join where the tube goes into the socket and it was pulled into joint. As the tube is clear you can see if you have a good bond. Repeat this for other end.
This sealed fine for me as it ran for a few days. However I had a small leak where the hose tail screwed into the reducer bush. As fixing this required removing reactor again and sealing threads with silicon I took the opportunity to run a bead of silicon around the tube just as a belt and braces to the polyweld bond. 

Next prepare the reducer bush to accept the CO2 intake and the valve for venturi or bleed. For this you need to drill two holes in the bush. 









You're wanting to drill the holes in the "sweet spot" ensuring that you don't break through the outer threads nor the inner.
In the first photo you can see small indents in the moulding around the outer edge of the top face. You want to drill directly between a pair of these and roughly in the centre of the material. If you're central to these indents then the tubes should have an intact web supporting them on either side as in second photo. 
I drilled a pilot hole of 3mm first- drill at a slight angle so that you avoid breaking through the external threads. Then open the hole so it's a nice snug fit around the 7mm tube; I can't honestly recall if this was 7mm or 7.5mm.

To prepare the white PVC tube cut one length so that's it extends almost to the bottom of the clear reactor tube (see photo in original post). Cut the second one about 50-60mm long so it only extends slightly into the reactor.
You'll notice in one of the photos above I show a check valve in the CO2 intake line. Nice idea but it desolved and snapped off when I applied polyweld to whatever plastic it was made from! Therefore I just used a straight 4mm airline connector. You can also see I have cut the mounting pad off the blue algarde inline valve. 
To fit the blue connector and inline valve into the white tube you need to use a drill to open the ID slightly until they are a tight fit. I used the polyweld to bond the fittings into the white pipe. Once set for extra security I applied some araldite. I then used polyweld to bond the tubes into the prepared holes in the reducer bush. Again for extra strength I applied araldite around both top and underside where the tube passes through the webs. When applying to top don't put too much so that the hose tail won't seat. 






Once set trial fit the bush with white tubes into the reactor. The bottom end of the long CO2 inlet tube will probably be contacting the inside of the clear reactor tube because the hole was drilled at a slight angle to avoid threads. This is easily resolved by softening the upper part of the tube in the steam from a kettle and bending so the injected bubble will be roughly central. 

I originally only used PTFE tape on threads but as mentioned I had a small leak. I'd therefore suggest using silicon on the threads when screwing together. Don't over tighten; especially the hose tails as the wall is quite thin and they'll easily snap. 

All you need to do now is add the venturi loop and hose configuration to suit your set-up. To install the 16mm ID Ehiem hose onto the 22mm tee and 20mm hose tails soften in either the steam of the kettle or dunk the end in a boiling kettle. 

Hopefully that's of assistance.

B4M


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## LondonDragon (25 Apr 2010)

Seems a lot of work and expense when you can get an Aquamedic for Â£60, I purchased an AM1000 from TGM for Â£60 and so far I am getting good results, just not happy with the Bio Balls inside the reactor, Matt suggested an easy way to create a venturi look on it so will give that a go or will get rid of the Bio Balls.


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## B4M (26 Apr 2010)

LondonDragon said:
			
		

> Seems a lot of work and expense when you can get an Aquamedic for Â£60



Hmm..wasn't the reaction I'd hoped for given the positive interest you and many others showed in Ed's. 

The cost of the reactor is actually Â£40. The venturi and other items are optional extras to suit my cabinet and would be needed for a purchased unit also.
I just checked and I didn't buy direct from Fantasea due to their hefty online postage. They are also on ebay found by searching seller: fantasea_aquatics. Via ebay their postage is much cheaper; if items are not shown just ask.

B4M


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## SKP1995 (26 Apr 2010)

Also, isn't the AM1000 12/16mm hosetails?  You'd have to buy extra parts to step down from 16/22mm hoses and I'm assuming there would be a slight impact on flow as well.  Then again, you could probably just build the hosetails up with PTFE tape or something I suppose, but either way I still reckon I'll be building my own when I can afford all the parts.


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## LondonDragon (26 Apr 2010)

B4M said:
			
		

> Hmm..wasn't the reaction I'd hoped for given the positive interest you and many others showed in Ed's.


At the time the AM was a little more expensive and Ed came in at about half price, and since that never materialised there was nothing else other the the German site on ebay or the AM 1000.

I have spent a lot of cash on all various diffusers and the AM does a great job, just removed the Bio Balls this evening, works much better now. 

All I wanted to say was that its a lot of work and expense for people like me that are not great at this DIY stuff and I rather buy a complete product than make myself one and risk leaks etc.. and plenty of headaches.

If you hunt around I am sure you can source the parts cheaper still and make a great reactor, like Ed was doing buying the stuff in bulk and making many at a time to reduce the costs.

I have nothing against DIY mate, if people feel confident about it and then you make it to suit your needs, great


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## LondonDragon (26 Apr 2010)

Piemonster said:
			
		

> Also, isn't the AM1000 12/16mm hosetails?


Nope the newer versions have 16/22, you just need some clips to secure it in place, it no longer looks like the photo on the website, I have actually mentioned it to Graeme at TGM to update the photo on the website has its misleading and probably costing them some sales, I had to cut the 12/16 reducer off to leave just the 16/22mm.


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## SKP1995 (26 Apr 2010)

Good to know, as you say, it's a bit strange that no retailers mention this seeing as it's possibly the biggest stumbling block to anyone using filters with 16/22mm piping.


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## LondonDragon (26 Apr 2010)

Piemonster said:
			
		

> Good to know, as you say, it's a bit strange that no retailers mention this seeing as it's possibly the biggest stumbling block to anyone using filters with 16/22mm piping.


That's why I didn't purchase one on-line and waited until my visit to TGM earlier in the month to actually have a look inside the box and check the connector as another member (Ceejay) purchased one and said it came with the right connectors and had to cut his to size too.


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