# Other Aquarium Forums > Equipment and Accessories > DIY Projects >  DIY External CO2 Reactor - Really worth the risk ?

## dc88

Quite a number of infor on the web on how to DIY an external CO2 reactor using PVC pipe and fitting.

One such example in this forum :

http://www.aquaticquotient.com/forum...ad.php?t=12259


I noted generally most of them experienced some lost of flow rate, presumelly was due to the bio-balls in the reactor got pushed to the end of the reactor pipe (due to the water flow) and partially block the water exit tube.
May be using lots of smaller ceramic ring chips instead of bio-balls, or add some form of grid screen near the end of the reactor pipe may solve this problem.
Increase the filter flow rate will only increase the water pressure acting on the bio-balls and cause more blockage.

Another question is that in the event of leak or worst case a catastrophic incidence (may be burst of pipe joint due to poor sealing method) the conseqence would be simply unspeakable ! Can you imagine an external canister pump draws the water from the tank at full pressure head out the bursted reactor pipe joint, combining the siphoning of the water from the tank via the reactor outlet end to the burst joint will empty the tank in no time !

All these risk against the benefit of more efficient CO2 reaction does it worth a trial ?

Very tempting to dive in and build one.... 
any advice ?

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## |squee|

It's the same risk we take in using any equipment imho  :Razz:  I made sure that I built it properly, sealed it up tight. Also, mine was a 2ft tank, so the damage if possible is much less than say a 3ft or 4ft. 

If yours is a big tank, why not try DIY-ing the internal one by Tom Barr? Looks small, neat, and it works perfectly (if not better than my example). I'll strongly recommend you to do the internal one compared to mine. I believe I posted up at the end that the reactor wasn't working well. What's more, the internal one means even if there's a fault the water will be still in the tank.

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## dc88

Thanks Terence

I may still make one for fun. Think it can also be used as a temporary inline filter module ? (with some quick connect tube connectors after the canister outlet flow) for quick water fix (such as filter thru carbon to remove yellow tint or remove fish medication) - just shut the CO2 inlet with an air-valve. 

I actually started collecting pipe fittings including clear PVC pipe....

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## Johnc

I think the reason, Terence's did not work is because of the position of the water inlet and outlet. For it to work, they must be positioned at the *side* of the cylinder rather than at the *end* of the cylinder. If the inlet and outlet are position at the end, the water will just flow through. If they are position at the side (near each end), the turbulence resulting will dissolve the CO2 (and spin the bioballs).

I DIY'ed mine using a 3 bio-ball internal reactor... Just removed one of the balls and all the ceramic rings. I have been using it without any problems for more than 6 months. Initially I thought it was going to clog up because I had it attached to the filter inlet rather outlet. But I have not needed to clean it at all... all these while.

/John

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## PeterGwee

> I think the reason, Terence's did not work is because of the position of the water inlet and outlet. For it to work, they must be positioned at the *side* of the cylinder rather than at the *end* of the cylinder. If the inlet and outlet are position at the end, the water will just flow through. If they are position at the side (near each end), the turbulence resulting will dissolve the CO2 (and spin the bioballs).
> John


No, that is not the case (he mention that it clogs often...thats a maintenance issue.). Unless you have a torrent flow that exceeds the reactor capacity (bubbles escaping from the outlet), you should have relative good dissolution as long as the flow is high enough.

Regards
Peter Gwee  :Wink:

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## dc88

Heres another one. Notice the connection : water and CO2 flow in from top, water exit at bottom of reactor.

http://www.users.bigpond.com/rohan.t/DIY_CO2.htm

May be Terence's design can fine tuned to shift the CO2 inlet to closer the water inlet ?

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## |squee|

> No, that is not the case (he mention that it clogs often...thats a maintenance issue.)


Yeap... the website which I based the reactor on also mentioned the need for a prefilter I think. 

Why an external reactor though? I've a feeling Tom's internal one will work better... it's small for a big tank imho.

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## dc88

> Why an external reactor though? I've a feeling Tom's internal one will work better... .


Good question. I am not too sure myself now, may be just want to get it out of the system... "being there, done that" kinda thing... so heres my version of it, even if it may not work well, never try never know.. :-


All parts are of local (Singapore) sources from various hardware shops.

Intended water and CO2 inlets from lower left, exit upper right, to be mounted vertically with flow from top to bottom (from canister to reactor to tank). 

To prevent the balls from been pushed to block the flow I added a "screen" at the end (simply made from a piece of cutout from plastic container and punched holes) :



Just completed few hours ago, should be ready to test-run tomorrow.

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## |squee|

Looks very well-done! Do post results of them here  :Well done:

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## dc88

Heres the test run :



Bathtub is for as safety measure : )
Connection : Cannister outlet to top of reactor and exit at bottom back to tank. CO2 enters at the top near the Reactor inlet thru a check valve. A T-joint there with a air valve is for priming the reactor and for venting stagnent air pocket in the reactor if needed.
Observation: For the first 10 min no major leak (Phew !) some small leak at the screwed joint of the coupling (need more telfon tape later). So far so good...
The flow rater was just right, I can see one bio-ball spinning. Heres the video clip :

http://web.singnet.com.sg/~dslchua/p...arium/spin.mpg

Conclusion after an hour running : CO2 level compare to before (the taiwan 3 balls internal reactor) - can't see any difference - the JBL CO2 indicator has no change. Anyway after 2 hours running decided to stop and disconnect it aside. Need to fix the leaking joint.... but its quite satisfied to see something from concept to working stage.

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## xxdivinityxx

Here comes the magical question.
Whats the cost?

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## dc88

Hi Jerome

It's a prototype : ) you know what I mean...
you can't compare a prototype cost to a commercial mass production cost. There is also the "R&D" expenses too because there were a few failure attempt before this last version. Although this last version is still cheaper than high end commercial product of similiar design (e.g. dupla external reactor). Heres the "magical" answer: if not for the clear PVC pipe would be around S$30 if a normal plastic pipe is used instead. With clear PVC it blows the cost to about $40. It can be lowered to $20 if used non-serviceable fixed ends design (as in Terence's design).
But I don't recommend anyone to replicate this for the sake of better CO2 disolving efficiecny. The taiwan brand internal reactor is still more practical and efficient (CO2 and cost wise) IMHO. (They probably also take a few development cycles and cost to perfect the "swirling-balls" design).
Its for hobby, my friend !
-------------
DC

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## PeterGwee

> Hi Jerome
> 
> It's a prototype : ) you know what I mean...
> you can't compare a prototype cost to a commercial mass production cost. There is also the "R&D" expenses too because there were a few failure attempt before this last version. Although this last version is still cheaper than high end commercial product of similiar design (e.g. dupla external reactor). Heres the "magical" answer: if not for the clear PVC pipe would be around S$30 if a normal plastic pipe is used instead. With clear PVC it blows the cost to about $40. It can be lowered to $20 if used non-serviceable fixed ends design (as in Terence's design).
> But I don't recommend anyone to replicate this for the sake of better CO2 disolving efficiecny. The taiwan brand internal reactor is still more practical and efficient (CO2 and cost wise) IMHO. (They probably also take a few development cycles and cost to perfect the "swirling-balls" design).
> Its for hobby, my friend !
> -------------
> DC


Doesn't matter if its dupla or not, a DIY version of yours would work well as long as the flow rate is strong enough with respective to the tank size. The more flow the reactor gets (within the capacity of the reactor...as long as you don't get burping of CO2 bubbles early in the day, you are fine.) the better the reactor operates.

By the way, can I know what did you get the parts?

Regards
Peter Gwee  :Wink:

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## dc88

Hi Peter

All the gray color fittings and the clear PVC pipe were from :
Top Vat Service Pte Ltd
Blk 25 #01-124 Pioneer Road North S628469
Tel: 62611513

I found this workshop by accident, they stock all sort of PVC material and some pipe fittings, and sell the pipe by cutting to your spec. The caveat is that their piping size seems to be mostly US's NPS size. E.g. the clear PVC is 2" or 1 1/4" which only goes with their gray color fitting. There are few other shops around there that sell pipe fitting too so you can compare pricing. 

(BTW my design is 1 1/4" pipe size, which is to match my filter flowrate - an Ehiem pro2222, if using 2" pipe size for my case would not have enough water flowrate as you commented. I then compensate the smaller size with longer length so to retain the CO2 bubbles longer.) 

The blue color barr fitting (size is 12mm tube to 3/8" thread) was from :

Hai Chew Hardware & Co. 
Block 153
Serangoon North Ave 1
#01-502
Tel: 62844445

The rest miscellanous were from Homefix DIY shop (tube clamp) and LFS (air tube connector).

Heres the exploded view of the assembly :



(note the air hose connector was later changed to the white color L-shape one, which I tap screw thread on it and to the pipe for better sealing.)

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## sacy

sorry. can buy e int-reactor from (UP) e green wan to make it to ext wan ma. cheaper NA sell 16 only. buy PVC Glue to Glue up e joint can liao. work for mi
^^

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## dc88

Thanks Sacy

No doubt. Good suggestion.
Life's liked that sometime, you go one big circle and the simplest way may work the best.

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