# Other Aquarium Forums > Equipment and Accessories > DIY Projects >  DIY external reactor using AMDUS water filter

## Shadow

Would like to share my DIY external reactor using AMDUS water filter. Some peple call it NA external reactor. Love this NA external reactor because it is easy to clean and easy to make  :Grin: 

The parts are shown below:


Parts list:
1) AMDUM water filter canister $17
2) 3/4 to 12mm hose connector: $3.50 (Hose size can be anything 12mm, 14mm or 19mm)
3) DYMAX CO2 atomizer (can't remember the price, reuse my old atomizer $1~$2)
4) Less than 1ft 3.5cm outher diameter PVC pipe $0.60
5) Air hose connector (can't remember the price as well)
6) Epoxy glue

Total around S$27

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## Shadow

First by removing the red color button and replace it with air hose connector. Glue it with epoxy glue. To remove, just unscrew the red button from inside. This red button was originally used to expell air trapped inside the canister.

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## Shadow

Secondly connect the CO2 atomizer to the air hose connector as show in the picture below. This is optional. You can also use those air stone, as long as it can fit.

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## Shadow

Next connect the 3/4 to 12mm hose connector to both inlet and outlet.

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## Shadow

lastly glue the PVC pipe to the blue color filter head and you get your self DIY external reactor.  :Grin:  You can also add couple of bio ball inside the canister, it will trap the CO2 longger. All done in less than 10 minutes except for the fact that you need to wait until the epoxy dry  :Razz:

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## yeoyl87

Clap clap clap  :Grin:  Nice and clear. Thanks for the hard work. 

Just a few doubts. Why PVC pipe? Where you add the bio ball? Inside the PVC? Outside? How the reactor works? 
Mix-Max uses the rotating blade to break up the air bubbles and thus allowing faster dissolving rate. Is it the same as in the case for bio ball?

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## Shadow

PVC look nicer  :Grin: , NA used hose, basically it is just to prevent the water from inlet go straight to the outlet. Just adding extra path. the bio ball is outside the PVC. The purpose of bio ball is to hold CO2 longer so that it is completly disolve into the water. The CO2 was break up by the CO2 atomizer.

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## yeoyl87

oh i see. Why not just filled up the canister with bioball? I think it also can prevent water from inlet going straight to outlet. Or even CR? can allow more media for BB growth  :Grin:  Does it work this way? 

Mod, maybe can make this thread sticky. I think it will benefit many new hobbyist in the future  :Grin:

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## BFG

The pvc end should have 90 degree bends to facilitate the water to turn in the reactor. Bioball is not needed in my opinion as the pressure in that reactor will force the co2 to be absorbed into the water. If you add bio-ball, it will slow down the water movement.

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## neon

> The pvc end should have 90 degree bends to facilitate the water to turn in the reactor. Bioball is not needed in my opinion as the pressure in that reactor will force the co2 to be absorbed into the water. If you add bio-ball, it will slow down the water movement.


What NA CO2 reactor has , is to put a 16mm hose with small little L-shape plastic and put the hose on the water filter head , no special glue is required.

Cheers

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## Shadow

> The pvc end should have 90 degree bends to facilitate the water to turn in the reactor. Bioball is not needed in my opinion as the pressure in that reactor will force the co2 to be absorbed into the water. If you add bio-ball, it will slow down the water movement.


The 90 degree bend at the end of PVC pipe may not be necessary, in my opinion it wont make any different. Bioball does reduce the pressure, in my case I always over rated my filter flow  :Grin:  8 to 10 times volume.

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## Shadow

> What NA CO2 reactor has , is to put a 16mm hose with small little L-shape plastic and put the hose on the water filter head , no special glue is required.
> 
> Cheers


that is true, but PVC look better  :Grin:

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## uklau

Bro, you may want to explain the direction of water flow to clear up the air about having a PVC pipe there. IMHO, L elbow is only needed if the water enters the canister from the pipe.

Well done! Thanks for sharing with everyone. Mine will be a variant of yours & I shall post it upon completion.

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## stephen chung

Robert, where did you get the canister from? Most of there selling like $35-39.

How is your reactor sited? Like the one selling in NA upside down or upright?

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## Shadow

For the canisted, you can try contact Li Liang at 9012 3684, you can also SMS him.

I put it up right. My thinking is CO2 (gas) alway move up in the water, thus if I put it upside down the undesolve CO2 will follow the flow and come out though the outlet. By putting it up right, the undisolve CO2 will be trap inside the canister. This is also the reaon why you can add bio ball, to trap the undesolve CO2 but flow rate will be effected.

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## stephen chung

> For the canister, you can try contact Li Liang at 9012 3684, you can also SMS him.
> 
> I put it up right. My thinking is CO2 (gas) alway move up in the water, thus if I put it upside down the undissolved CO2 will follow the flow and come out though the outlet. By putting it up right, the dissolves CO2 will be trap inside the canister. This is also the reason why you can add bio ball, to trap the undissolved CO2 but flow rate will be effected.


Robert,

Hmmm the Li Liang number I've got is different from yours. I just called him and his number is 9012 7020. The number that you gave belongs to some chinaman. 

Water that comes down from the pipe does not have a "stirring" motion. It is kind of hard for the co2 to dissolve is it? I think by putting a elbow will yield a better result.

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## vinz

> The 90 degree bend at the end of PVC pipe may not be necessary, in my opinion it wont make any different. Bioball does reduce the pressure, in my case I always over rated my filter flow  8 to 10 times volume.


The reason for the elbow is to make the water swirl in the chamber better.

Personally, I never liked the small black elbow used in the NA one. The exit is too small, thus restricting flow. The 90 degree elbow also obstructed water flow. I replaced it with a green curved one. The diameter is much bigger and the gradual curve should, in my opinion, cause less resistance. (E.g. you can't speed through a L shaped bend in a car, but you could easily power through a curve much smoother and faster.)

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## BFG

By having the bend, it will swirl the water in the reactor as what Vinz has pointed out. This swirling motion will force the co2 into the water at the top part of the reactor and also move AND mixed the water coming from the canister filter and the co2 enriched water in the reactor.

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## stephen chung

Robert, I also suggest that you put the diffuser all the way down to the bottom of the canister. Because right now the diffuser is at the outlet of the canister. Co2 might just got flush out before it could be dissolved.

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## uklau

It's inlet, uncle Stephen  :Grin: .

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## Shadow

> Robert,
> 
> Hmmm the Li Liang number I've got is different from yours. I just called him and his number is 9012 7020. The number that you gave belongs to some chinaman. 
> 
> Water that comes down from the pipe does not have a "stirring" motion. It is kind of hard for the co2 to dissolve is it? I think by putting a elbow will yield a better result.


arg... my mistake, it suppose to be 9012 7020, I mixed up the number  :Embarassed:

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## Shadow

> By having the bend, it will swirl the water in the reactor as what Vinz has pointed out. This swirling motion will force the co2 into the water at the top part of the reactor and also move AND mixed the water coming from the canister filter and the co2 enriched water in the reactor.


Thanks, you gave me an idea  :Grin: . Instead of having bend at the end of PVC, I force it to swirl around PVC pipe by re-directing the flow on the in let. It can be done easily using piece of plastic.

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## Shadow

> Bro, you may want to explain the direction of water flow to clear up the air about having a PVC pipe there. IMHO, L elbow is only needed if the water enters the canister from the pipe.


Here is the direction of water flow

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## uklau

Ideally, we want the water to flow that way (red lines) but trust me, it does not  :Grin: .

I put some coloring in the water to observe the water flow in one of my experiments.

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## Shadow

Yeah thats and ideal sketch  :Razz: 

Did you redirect your inlet flow?

How did you callor the water? what solution did you use?

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## vinz

If you want the water to flow like that, you need to stick an elbow (or curved fin) below the atomiser (in your design). If you use an elbow, you'll need to make sure its well sealed on the outside.

Actually, now your design makes more sense than before. Not a bad idea, but I think the bio-balls will stuck at the top due to the irregular surfaces.

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## Shadow

yes, that is the idea, but instead of elbow, I just used piece of thick platic glue it to the inlet of canister head 45 degree (inner side).

Not sure about bio ball, have not try that, may not even be necessary.

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## vinz

If you atomise the CO2, and the flow rate is high, you won't need bio balls. I never had to when I was running about 2000L/h on the NA version. I had to bubble pretty fast to satisfy the needs of a 6'x2'x2' tank. Not even atomised.

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## BFG

The picture is upside down. If you use it that way, the co2 will flow out in bubble form.

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## uklau

> How did you callor the water? what solution did you use?


Robert, I just pour some Ribena into the reservoir I used for testing  :Grin: . You may also use the debris from your canister filter, which is better than coloring.

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## Shadow

Ribena? I don't think that good for fish  :Grin: . Maybe just boost up CO2 and see where the bubble move.

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## Shadow

> The picture is upside down. If you use it that way, the co2 will flow out in bubble form.


I don't get what you mean? if it is upside down, then the un disolved CO2 buble will be suck into the PVC. Well never know until I try  :Embarassed:

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## Shadow

Picture of the piece of plastic to redirect the water flow.



DIY CO2 in action:

YouTube - DIY CO2 reactor in action

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## neon

NA method is to :

a) flip the filter up-side-down
b) the original water-in becomes water-out
c) the original water-out becomes water-in and a hose is connected to the centre of the blue-cap (where you put the PVC) and the end of the hose with elbow.
d) drill a hole at the cap (your case you use the red button) for co2

usage :
a) water will gush into via the hose and the elbow will create swivel effect
b) CO2 rise up and mix with the swivel water . Unresolve CO2 remains on top.
c) mixed water will move out from bottom 

I have this NA reactor, if the water too strong, a lot of bubble will be gush out. I preferred the long PVC pipe reactor stuff with bioballs rather than this reactor, as the later one mix is almost 100%.

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## Shadow

My design is a bit different than NA design.

a) Filter is up right
b) Use original in and out
c) The red button thingy located at inlet, one of the reason can switch the in and out (unless drill new hole).
d) Atomizer will help the dissolving rate
e) Redirect the input with piece of plastic (black thingy in the picture) to create swivel
f) Un-dissolved CO2 will be gathering in the inlet, thus there no way the un-dissolve CO2 gush out. Not sure if the water flow > 1200L/h though  :Razz:

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## illumnae

bringing up an old thread. how's the co2 reactor Shadow? any leaks? i'm considering DIYing 2 using your design  :Smile:

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## Shadow

No leaks. No drilling nor cutting any part of the filter, so it shouldn't leaks unless the filter is faulty. The only possible point for leakage is the CO2 entry if it is not glue poperly. Expoxy is prety strong glue, so should be ok.

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## illumnae

cool thanks Robert. I'll make 2 for my use then  :Smile:  do you always have to use the basin below the reactor as shown in your video?

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## Shadow

nope, I put inside the basin only during experiment.

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## dominik

I am now using a resun FR to act as a external CO2 reactor. The only modification you need to do is to drill a hole for injecting the CO2. This resun FR can be bought at 10 to 20 dollars for a second hand one.

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## illumnae

sorry what's a resun FR?  :Smile: 

Robert, do all the AMDUS water filters come with the red plug? and also where do you get the plastic you siliconed to direct water flow from? i notice it's curved at one side, i assume to fit the curvature of the PVC pipe?

I have been unable to find a suitable external CO2 reactor for my setup (Jaqno uses 12mm hoses with no adaptor, NA one is really pricey and ISTA one is reputed to leak, especially since i have to use an adaptor), hence your DIY which is solid and can fit 16mm hoses is very appealing!

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## dominik

> sorry what's a resun FR? 
> 
> Robert, do all the AMDUS water filters come with the red plug? and also where do you get the plastic you siliconed to direct water flow from? i notice it's curved at one side, i assume to fit the curvature of the PVC pipe?
> 
> I have been unable to find a suitable external CO2 reactor for my setup (Jaqno uses 12mm hoses with no adaptor, NA one is really pricey and ISTA one is reputed to leak, especially since i have to use an adaptor), hence your DIY which is solid and can fit 16mm hoses is very appealing!


Resun is the brand while FR means Fludisied Reactor. FR is use mostly in marine setup to remove PO4. You can just buy a second hand one that cost below $20(i just sold mine extra FR for $15). Drill a hole to inject CO2, put in some bio balls and there you have it. It could be acheive in less than $20.

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## Shadow

> sorry what's a resun FR? 
> 
> Robert, do all the AMDUS water filters come with the red plug? and also where do you get the plastic you siliconed to direct water flow from? i notice it's curved at one side, i assume to fit the curvature of the PVC pipe?
> 
> I have been unable to find a suitable external CO2 reactor for my setup (Jaqno uses 12mm hoses with no adaptor, NA one is really pricey and ISTA one is reputed to leak, especially since i have to use an adaptor), hence your DIY which is solid and can fit 16mm hoses is very appealing!


Yes they all come with the red plug, you just need to unscrew it and replace it with air tube connector. That black plastic thing is from unuse plastic cover  :Razz: . I just cut it to fit.

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## illumnae

haha ok thanks! i pmed the guy selling AMDUS water filters on AF, hopefully he'll reply soon.

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## ongtw

sorry guys,

where can i get all these items?

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## illumnae

i just called the guy who sells the water filters, total cost for filter housing + 2 connectors is $27, slight price increase from when robert bought his. i'll possibly work on it this weekend to destress from work even though i don't need it now :Laughing:

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## Shadow

$3 increase but it should still be cheaper than buying from those normal shop

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## illumnae

yup i'll be making the purchase for 2 units soon. thanks for the guide robert!

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## Shadow

your welcome

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## illumnae

just to confirm, i should be using epoxy and not aquarium safe silicone to seal the co2 atomizer?

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## Shadow

You might not want to use the atomizer because it can get block easily. And yes all glued using epoxy. The brand I was using is "Araldite" no issue with the shrimp.

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## illumnae

dont use the atomizer? what should i be using instead?

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## Shadow

I was since replace it with air tube connector.

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## illumnae

would the rate of dissolving of the co2 be affected since it isn't broken up into smaller bubbles?

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## Shadow

ok for my case, but only 3 bps. Maybe try airstone which have bigger pore.

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## illumnae

i've made my order for 2 AMDUS water filters to kickstart this project  :Smile:  hope my DIY skills are good enough  :Opps:

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## illumnae

i bought Selleys Knead-it Underwater today, it's safe for contact with drinking water and comes in putty form so it's easier to manipulate...do you think it's suitable? it's something like this, just that in Singapore it's called a different name:

http://www.selleys.com.au/Selleys-Kn...a/default.aspx

robert, can i check with you the length of the PVC please? is it 9 inches (since the tap water filter is 10 inches)? would the clear plastic tubes sold at c328 do or is PVC better?

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## Shadow

you are right 9 inches, not sure about the "selleys" though. I thing PVC is easier to glue, I always having problem with those clear acrylic pipe

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## illumnae

i have gotten the PVC pipes and have already epoxied the airline connector to the airhole. it's really very easy! the airline connector fits very snugly into the hole, so not much fear of leaks...the epoxy is only a "just in case". the way i did it though, there's no way i can fit an atomizer in even if i wanted to...i hope it's good enough  :Opps: 

Robert, i need advice on what to use for the water flow director! haha, i can't seem to find any suitable piece of plastic! once i find that i can finish my reactors very fast

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## Shadow

I use left over ice cream container (those 1 or 2 liters one) and cut it to necessary size  :Grin:

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## illumnae

good reason for me to buy ice cream! haha.

aren't those containers rather flimsy though?

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## Shadow

yeah it is, which is good think because easy to cut  :Opps: 

I would say that any plastic container will do.

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## illumnae

ok i'll try. hopefully the flimsy plastic wont give way!

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