# Planted Tanks > Plant Talk >  Reactor or Diffusor

## loupgarou

if money was no objection, which is your choice?

I already have one of the better co2 reactors on the market, however, I find the setting up (tubing) is quite a hassle due to the fact that it needs a pump to run it. initially, I hooked it up to filter output, but now I'm going to move it to chiller output. but I think the tubing is a real hassle when you take the filter or chiller for maintenance and want to clean up the hoses as well.

I'm beginning to find the glass spiral type of diffusors extreme attractive now due to ease of maintenance.. (ie: just bleach, won't clog)...

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## PeterGwee

An external reactor for sure. Response time is very fast with those high flow units.

Chris, why not run it using an individual powerhead instead. I run mine off a maxi-jet 900 (235gph) hooked up to the light timer. The Aqua Medic Reactor 1000 is a pretty good reactor in my opinion. If only we can get the pvc reducers easily in singapore, DIY is better. (I haven't had much luck getting those 2" - 0.5" reducers and 0.5"- 1/4" barbs.).

Regards
Peter Gwee  :Wink:

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## wf7850

The choice would also very much depends on the size of tank. i believe for tanks larger than 4ft, one will need a reactor to acheive maximum CO2 dissolve rate. as fer smaller tanks, the spiral diffusor shld do the trick.... and for even lesser maintenance, those ceramic types (like airstone) shld be just fine.....  :Smile:

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## loupgarou

yeah, the thing is, I would then have chiller pipes and filter pipes AND co2 pipes..

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## |squee|

Money is the problem for me basically when considering a reactor. Not to mention the hassle and pipes and all that too. However, if money isn't a problem, of course I'll go with a reactor.

The ceramic diffusor is a more practical choice for me now  :Smile:

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## Nicky

[quote:c13faaade2="|squee|"]Money is the problem for me basically when considering a reactor. Not to mention the hassle and pipes and all that too. However, if money isn't a problem, of course I'll go with a reactor.

The ceramic diffusor is a more practical choice for me now  :Smile: [/quote:c13faaade2]

If you DIY your own reactor, you may be surprised that there are little diff in cost when you compare the 2.

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## loupgarou

anyway, I resolved the issue. just wired it up to my chiller anyway.

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## |squee|

[quote:d9891aaf16="Nicky"]
If you DIY your own reactor, you may be surprised that there are little diff in cost when you compare the 2.[/quote:d9891aaf16]

:P I'm not really a handy person, and the size numbering systems and all that are greek to me. I'm not sure that my fliter's flow rate is fast enough too... so  :Confused:

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## benny

I've used interenal and external reactors as well as diffusors. I find the internal reactor to be the least trouble some. Especially if you have two. Just replace the dirty one while you soak the soiled one in very hot water.

Diffusors are more suitable for smaller tanks up to 2 ft in size for asthetic reasons.

Cheers,

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## foxxkat

i vote reactor..  :Smug:

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## catus36

I vote for reactor, although it is quite troublesome to set up
as Benny has said.

For internal reactor, it will get dirty overtime and is a chore to clean it
External reactor is better, however, the fear for leakage there.

To get the best of both world, use both.
One at each end. That's what i think.

Cheers  :Smile:

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## theodore

My vote goes to diffuser. I just love the look of my ADA beetle  :Kiss:

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## juggler

> I've used interenal and external reactors as well as diffusors. I find the internal reactor to be the least trouble some. Especially if you have two. Just replace the dirty one while you soak the soiled one in very hot water.
> 
> Diffusors are more suitable for smaller tanks up to 2 ft in size for asthetic reasons.
> 
> Cheers,


Reactor for me. Don't think they will ever get choked. Dirty also never mind since it is hidden behind the plants (mine is the 3 ball internal type). Negligible maintenance.

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## e-mini

Internal reactor for me as I don't have to worry about water leakage problem.

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## Heuer

Since we are on this topic, will it be better for large tank (eg 5/6ft) to have 2 CO2 injection points (2 ext reactors connected to 2 ext filters with one CO2 sys using a 2way spliter which can get from NA).

I think in theory, this will dissolve CO2 faster and better distribution around the tank.

we can also clean one filter without affecting BB on the other.

Anyone got such setup and share your experience.

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## Lemonz

A few thoughts:

I think the idea of having two inlets is very good for a big tank (>5ft)!

One thing that I am unsure, since the plants take in dissolved CO2 in the water, isn't reactors the best since they allow the CO2 to dissolve more thoroughly then diffusers? The latter only makes ultra fine bubbles of CO2 to increase the rate of dissolving? Ultimately its the dissoled CO2 that counts right?

If that is the case, reactors are definitely better? I can introduce 1bps yet the rate of dissolving still allows CO2 to accumulate in the reactor, until they can dissolve into the water. So actually I save on CO2, is it? No point pumping so much CO2 into the water when theres only so much it can take? Since the plants also take in those that are dissolved in the water?

Any advice?

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## |squee|

Yes Lemonz, a reactor is definately better, and allows for lower bubble count and higher/faster saturation of C02.

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## Heuer

Hi Lemonz,

This is exactly what happen when i switch from diffusor to reactor. When i was using diffusor, i set it at about 4 bubble per sec and getting a pH of 6.5, after switch to reactor and with the same bubble count, pH down to about 6.0. Therefore, we need to make fine adjustment to CO2 injection.

Using chiller will also have a lower pH with the same amount of CO2 injection as compare to a tank without chiller.

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## kayser78

reactor better. minimal loss of co2 => means co2 can last longer => means less frequent to carry the heavy cylinder for top up 
+ no maintenance at all (at least to me)

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## vinz

> Since we are on this topic, will it be better for large tank (eg 5/6ft) to have 2 CO2 injection points (2 ext reactors connected to 2 ext filters with one CO2 sys using a 2way spliter which can get from NA).
> 
> I think in theory, this will dissolve CO2 faster and better distribution around the tank.
> 
> we can also clean one filter without affecting BB on the other.
> 
> Anyone got such setup and share your experience.


You don't need 2 reactors... one reactor is efficient enough. But you need to split out the return to the tank. I'm running a 6 foot tank with the following setup.

+-> tank left side
|
splitter <- chiller <- reactor <- filter <- tank
|
+-> tank right side

You don't need to worry about extra CO2 equipment, (CO2) splitters, etc.

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## Lemonz

Hello Vinz!

Hmm.... thats a good way to have two inputs. Dun need to get two filters...

One question though... will putting the chiller before the reactor allow more CO2 to dissolve in it?

Or why do you set up in such a way?

Ray.

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## |squee|

> One question though... will putting the chiller before the reactor allow more CO2 to dissolve in it?


I'm not vinz, but here's a recent discussion.

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## Heuer

> You don't need 2 reactors... one reactor is efficient enough. But you need to split out the return to the tank. I'm running a 6 foot tank with the following setup.
> 
> +-> tank left side
> |
> splitter <- chiller <- reactor <- filter <- tank
> |
> +-> tank right side
> 
> You don't need to worry about extra CO2 equipment, (CO2) splitters, etc.


Hi Vinz,

Thanks for the info. If i don't read your diagram wrongly, your CO2 enrich water will be chill by the chiller before going back to the tank. Will the CO2 enrich water damage the chiller as CO2 is acidic.

Ah Tan from Bioplast told me not to configure this way. My config is 
Filter->chiller->reactor->tank.

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## fishshy

Reactor is very much better. Glass diffuser may look nice & good when it is new. But after a period of use, u will find it is more troublesome to maintain it.

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## vinz

> Hi Vinz,
> 
> Thanks for the info. If i don't read your diagram wrongly, your CO2 enrich water will be chill by the chiller before going back to the tank. Will the CO2 enrich water damage the chiller as CO2 is acidic.
> 
> Ah Tan from Bioplast told me not to configure this way. My config is 
> Filter->chiller->reactor->tank.


 My chiller is from Ah Tan, but he never told me this.

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## tawauboy

> Hi Vinz,
> 
> ..................... Will the CO2 enrich water damage the chiller as CO2 is acidic.
> ..........................


it is a weak acid. doubt it will damage your chiller within the chiller lifespan.

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## c.y.

> An external reactor for sure. Response time is very fast with those high flow units.
> 
> Chris, why not run it using an individual powerhead instead. I run mine off a maxi-jet 900 (235gph) hooked up to the light timer. The Aqua Medic Reactor 1000 is a pretty good reactor in my opinion. If only we can get the pvc reducers easily in singapore, DIY is better. (I haven't had much luck getting those 2" - 0.5" reducers and 0.5"- 1/4" barbs.).
> 
> Regards
> Peter Gwee


Hi, Peter Gwee,
I am using a used filter(atman 3336, 800L/H) to run the external reactor(from NA) for my 3ft planted tank. I feel that the water back to tank is very weak, I hardly feel the current when I put my finger near rain bar. Hence, I worry that the dissolved co2 did not evently distributed in my tank. Thinking of using a powerhead to run the reactor, can you advise how do I connect it and what type and what flow rate of power head should I use.

Thank you.
Seah

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## PeterGwee

Seah, have you measured the results of how well your reactor is working? CO2 24/7 or "on" during the day? What kind of measuring equipments are you using to measure both pH and KH? Consider taking measurements when you do a large water change and see how fast the CO2 system needs to get the CO2 back to good levels. It should take only about an hour or so for a fast responsive system. Aim to do that..
1)You can consider adding more flow to the reactor till the capacity limit of the reactor in which CO2 bubbles will be burped out prematurely.
2)Add more current/turnover across the the outlet of the reactor and tank.
3)If the above 2 methods does not get the responsiveness you like, you might have to add another unit or so to increase the responsiveness. Its nice to get manifolds for the regulator but hurts the wallet.  :Razz:  )


*CO2 stability during the photoperiod and the responsiveness of the system to get the CO2 up to "good" levels from ambient levels within an hour or so is what most folks should work on.*

Oh, like Tom Barr mentioned recently, try to turn off all equipments first before doing the measurement with a pH pen/monitor to prevent stray currents from affecting the results.

Regards
Peter Gwee  :Wink:

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## c.y.

Thanks Peter,
I on the co2 together with light for 7 hours a day. Co2 set at 3 -4 bpm. Have used ph and kh test kits(something Sea brand, cannot remember) tested the co2 level. It is around 30ppm may be more(I have dificulty in reading ph colour chart.  :Embarassed:  ) The testing is done after light/co2 on for 2 - 3 hours. I shall try it in 1 hour time when next water change. 

I feel that the flow back to the fish tank is very weak, I hardly feel the current when I place my finger near to the rain bar, so I am thinkng of using a powerhead to run the reactor instead of the filter, but do not know how?

Thank you and best regards,
Seah

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## cherietung

> Since we are on this topic, will it be better for large tank (eg 5/6ft) to have 2 CO2 injection points (2 ext reactors connected to 2 ext filters with one CO2 sys using a 2way spliter which can get from NA).
>  
> I think in theory, this will dissolve CO2 faster and better distribution around the tank.
> 
> we can also clean one filter without affecting BB on the other.
> 
> Anyone got such setup and share your experience.


In order to use the setup as written by vinz, you need to use an external reactor which is the big water filter converted into a reactor. To me, it takes up space inside the cabinet. But it is really effective.

I use 2 filters with 2 co2 & 2 reactors. one of the tubes goes to chiller while the other goes into uv light. In the event that one co2 bottle is empty, the other can continue the co2. Mine is 5' tank. Moreover, internal reactor are smaller and reduce the risk of leakage.

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## a_scape

Hi friends,
I vote for reactor.
I've been using the AquaMedic (Aqualine Buschke) model Reactor 500 since 5 yrs ago (if not mistaken this still the most expensive in the market US$60/unit)?
Use 1 unit (run with 2 bubbles/sec) for tank 150x60x60 without any problem 
Cheers,

AChen  :Flame:

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## gchoo

> My chiller is from Ah Tan, but he never told me this.


I think both are fine as long as it conforms to the required chiller flow rate.

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## michael lai

My personal findings is I'll use reactor for 3 ft tank and above and diffuser for 2 ft tank and below. Agree with the guys reactor would dissolve Co2 faster than diffuser but only for the hassles of the tubing.  :Smile:

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## Plantbrain

Ya'll might want to look at the 2$ reactor design I have on the site. It's free to view for anyone that wants to make it.,.

If the moderator would like, I can send the images and DIY article etc for your site and a sticky.

I like Reactors, I use both, I've built perhaps 25 different designs over the last 15 or so years.

I also use diffuser stones on small tanks for aesthetic reasons or bubble the CO2 into those tank's filters. I like diffusers over filter intake.

Sump systems represent another type of CO2 reactor/Diffuser placement, here a very simple reactor can be made for 3-8$ that outperforms any thing on the market.

The internal design reactor I have can be used with DIY and be turned on during the day simply by plugging the powerhead into the light timer. A similar internal reactor, (mine is better) is made here and sells for 50$.

DIY external reactors cost about 10$ and can be run on a canister filter line or a separate powerhead.

Regards, 
Tom Barr


3rd annual Plant Fest July 8-14th 2005!
[email protected] Get connected
www.BarrReport.com Get the information

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## BPT

I vote to use both together  :Grin:  . Before, I used only diffusor on a 2ft tank fed into the input of canister filter. Few times a minute collected & undiffused CO2 bubles out of the filter.
Just this morning, I got a dead rainbow and other fish gasping for air after I added a reactor on the output of the canister filter last night without reducing the BPS  :Shocked:

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## evolim83

I would vote for a combination of both!
I have an external reactor and a diffusor!
When i started using the reactor, i removed my ADA diffusor and it sits in my storeroom collecting dust!
Then I tot, might as well add in the diffusor as well for aesthetic reasons!
The results turn out good!

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## neon

> My chiller is from Ah Tan, but he never told me this.


Most chiller now is titanium coil and built for marine water also, which is don't know how many time more corrosive than the weak acid that produced from the co2 reaction.

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## riccia

me using reactor. the 3 ball internal type. just 1 tube to the top of the reactor (inlet) for CO2. it's working well for me.

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## stmoo

reactor / diffusor its all depend on the size of the tank. they all works well. 

for me, my 1ft at home and 2ft in office is using diffusor. they are all doing well.

and reactor for the 4ft at home. 

i vote for both.

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## Kev0055

Doesn't matter much to DIY CO2 folks since they can't control the rate anyway.
Just go for the most aesthetically pleasing and budget type, or simply hook it into the filters or water outlets.

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## scorpio75

for me i use sera co2 reactor.fine for me.

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## Plantbrain

Here's a pic on my DIY 2$ reactor:

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## Plantbrain

Here's some more and note the screwdriver and lighter which is used to burn/melt the holes into the sides.

Also there's a bottom up view of the angled 90 degree spiral flow, this removed the need for a sponge etc.

The outflow only allows very fine mist that can be blasted around the tank from the main filter flow.
The burp hole allows excess CO2 to belch out when the powerhead is off or if you want to stop tyhe CO2 from being diffused, so you can use it in semi automatic for the night time off ability for the DIY yeast folks.
Simply plug it(the rio 180) into the same light timer.

Took me 15 min to make this and a total of 12$ for the rio pump as well.

See my site for more, the pic limits here are eating up the images I've posted.
Search DIY internal venturi reactor.



Regards, 
Tom Barr

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## FishFan

Tom, great job! We need a detailed guide.  :Smile:

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## StanChung

I've retired all three reactors I have and use diffusors in all three tanks. I find the results are good without the extra equipment in the tank.

I think a little more CO2 is wasted but I save power on the extra powerheads I need to drive it.

Regards

Stan

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## bk707

> if money was no objection, which is your choice?
> 
> I already have one of the better co2 reactors on the market, however, I find the setting up (tubing) is quite a hassle due to the fact that it needs a pump to run it. initially, I hooked it up to filter output, but now I'm going to move it to chiller output. but I think the tubing is a real hassle when you take the filter or chiller for maintenance and want to clean up the hoses as well.
> 
> I'm beginning to find the glass spiral type of diffusors extreme attractive now due to ease of maintenance.. (ie: just bleach, won't clog)...


If money was no ojection.. I would get the Dupla Reaktor 400 or Reaktor S depending on the size of your aquaria.. but remember the get the cleaning kit for the algae. I studied the water flow in the device and find it really good. Problem is.. its expensive... 

In most of these devices.. gotta agree with you.. the tubing sucks.. really have to plan really well.. else end up really looking bad.. that's where it seperates the boys from the men.. i guess..  :Grin:

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## FC

I saw an interesting external reactor, see
http://www.killies.com/forum/viewtopic.php?t=3300
What do you think?

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## bk707

I suppose this will work. And I think its cheap enough to buy and try. The Dupla one that I am using is really great... but then again, I am stuck with it, simply because I bought it at such a good price.. (original price was $120) and I got it from $10.

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## Plantbrain

The DIY version of my internal reactor and the DIY version of the external work extremely well.

Much smaller than this thing above and works better for internals.
Used the Dupla line about 10-20 years ago, too $$ and was not that good, not enough flow, poor results vs the DIY 2$ reactor. Sad.

Regards, 
Tom Barr

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## Cacatuoides

Are there supposed to be pictures attached?

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## FC

You can see the picture at:

http://www.killies.com/forum/viewtopic.php?t=3300

I think it is going at $21 for the large one, a bargain for a well designed external reactor, in my opinion.

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## Betta Almighty

> The DIY version of my internal reactor and the DIY version of the external work extremely well.
> 
> Much smaller than this thing above and works better for internals.
> Used the Dupla line about 10-20 years ago, too $$ and was not that good, not enough flow, poor results vs the DIY 2$ reactor. Sad.
> 
> Regards, 
> Tom Barr


Do you have a picture of your DIY External Co2 reactor?
Cant seem to view the precious one.

Thanks

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## KeIgO86

with regard to the external reactor from the link, I see another problem. The inlet and outlets seems like it won't be able to be secured properly, considering that there's no grooves or any sort to hold the tubing. water pressure might just POP open the tubing and you will have an epic flood in your home. And the inlet/outlet isn't made of metal, so using those hose tighteners, if you tighten too hard later the reactor crack thats it.

Any comments?

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## blackBRUSHalgae

> with regard to the external reactor from the link, I see another problem. The inlet and outlets seems like it won't be able to be secured properly, considering that there's no grooves or any sort to hold the tubing. water pressure might just POP open the tubing and you will have an epic flood in your home. And the inlet/outlet isn't made of metal, so using those hose tighteners, if you tighten too hard later the reactor crack thats it.
> 
> Any comments?


I secured mine with metal fasteners with no ill effects.

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## Betta Almighty

You guys got any pics of your DIY external Co2 reactor?

Thanks and Regards

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## ballsmyberries

i'm currently temporary using a airstone on my DIY CO2 my newly setup nanotank. i do have a diffusor but it's running on my main tank. just wondering, is it enough or do i need to get a glass diffusor?

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## StanChung

Hi Jason,
Your DIY CO2 will not be able to generate sufficient pressure to push the bubbles out of a glass diffusor. Put the outlet near your HOB [assuming you are using one for your Nano] to chop up the CO2 bubbles.

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## Ssur

Anyone got recommendation for a reactor or diffusor suitable for a 1 feet cube tank? Presently using a glass ceramic one from NA, but wouldnt mind upgrading it. 

ADA? Aquamedic? What else?

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## chaosdiablo

I vote reactor

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## Ziggy909

i have been using a diffusor in my tank for about 6 month..a pretty good dennerele pro system on a 280L tank.. i was getting through a 350g bottle a month, so i decided to drill a hole above my filter out take basket and glue the co2 tube directly into this.. the bubles of co2 get sucked in the filter and broken up by the filter before being returned to the tank via the spray bar...i keep the co2 rate down to about 1 bubble a second so as not to air lock the filter, and i also have it attached to a ph controler and solinoid. i am pretty happy with this arangement so far an i think that i am saving co2 as well....as long as the flow rate from my filter is no to fast....i chose this option as the cleaning involved in an internal reactor and external diffusors is problematic and it also takes equipment out of the tank... a bonus for me....also the use of check values is a must.... i really really recomend this setup for everone....

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## illumnae

i've seen some people on foreign forums use something called a mazzei injector and claim that it produced better results than an external reactor. anyone have experience with this or know where it can be bought in singapore?

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## heeroyu16

http://www.mazzei.net/products/injector_info.htm
For those who do not know what a Mazzei Injector is.

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## Shadow

does anyone try inline diffuser?

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## StanChung

I'm testing that. Seems to be working well. Another piece of equipment out of the tank!

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## Shadow

how is the efficiency? I'm using that as well but since it can only fit 2211 inlet hose (12/16), I can really see whether the CO2 mix because of the diffusor or 2211 impeler. Does algae grow on the inside? I would guess it will, especialy brown algae.

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## StanChung

The area you can see is the underside of the diffusor. The part being exposed to water flow cannot be seen except if you peek from the plastic connector opening.

Will still get bubbles flying around the tank like my other external [Cal Aqua]

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## Shadow

fine bubble or just big lump of CO2?  :Grin:

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## StanChung

Not really that fine but does the job well enough.

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## neon

Why not DIY with external PVC pipes ?

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## Shadow

did that before, problem is it is hard to clean. I can't find PVC screw able cap from local hardware shop.

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## Plant_Geek

Hi 

I voted 100% reactor. Inline are best IMO.

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## neon

> did that before, problem is it is hard to clean. I can't find PVC screw able cap from local hardware shop.


Those HDB estate hardware shop which sells PVC pipe should have the holder (with screw groove) and the cap. You just need to PVC glue the holder on the PVC pipe. If you are staying at HDB, observe it at the void deck area, you will know what I mean. 

The size of the pvc pipe depends on your pump/canister flow rate. Be prepare this will reduce your flow by few hundred litre/hr. I use eheim 1262 pump (3400L/h) on my canister. canister -> pump -> reactor -> chiller -> tank .

Drill one hole on the cap and get those brass hose connector with brass screw ring so it can secure firmly onto the cap, and of course put silicon seal before fasten the brass screw ring. Drill a tiny holes on 3/4 height from the bottom of the PVC pipe (slightly below the cap holder) for your CO2 injection. I bought those clear air connector from lfs and secure with silicon seal first, then covered with epoxy clay on the outside to cast it like a volcano. The co2 connector will be very secure and leak-proof. Cut a 4" air tubing with check-valve and tie with cable-tie on both end of the tubing.

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## o2bubble

I think reactor is the best in efficiency but reduces the flow rate a bit. Been using for a while and decided to try diffuser and bought Cal labs CO2 inline diffuser. Will provide feedback after sometime.

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## o2bubble

Just an update... Just started operation today. The cals labs inline diffuser produced alot of fine bubbles which were blown around the tank by the lily pipe. Seems ok but one thing to note is to invert the diffuser and turn back after clearing the air bubble inside. My plants have not really photosynthesis yet, only produced very fine and few oxygen bubbles. Will observe further.

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## Growe

Would vote for external reactor. A natural planted tank should have the minimun intrusion of equipment for that Natural look . Imagine a river bed with a diffusor / piece of internal reactor to pump CO2?!? :Grin:

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## EddyTing

Ya, I agree on that too. I personally do not wish too see much of 'man made stuff in my tank as it'll spoil the natural scene we're trying to bring out. I vote for reactor. :Smile:

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## ggMing

i too go for reactor..  :Smile:

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## madnugget

i'll vote for reactor! esp those NA external reactor! Just switch from ISTA co2 reactor to NA's and the improvement is significant! never had i seen my HC pearl so much under same condition

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## Fuzzy

Reactors are definitely more efficient, but the reason I go with diffuser is there is less maintenance involved, and you don't lose flow rate.

In smaller tanks with lower bps rates (1 - 3 bps) the CO2 consumption is not that high.

I was actually using the ISTA max mix also, performed excellent initially, then detritus built up around the spinning part after a month or two, affecting flow rate drastically.

Opened to clean it, which was seriously tedious because of the way the hoses join to the very brittle plastic. Then after 5 months fine cracks were starting to develop at the base, I tossed it out before it flooded my living room.

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## will

I own an UP diffuser, it works perfect

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## herns

Heres a good reading from Tom B.

*CO2 revelations*

CO2 is one of those critical things that aquatic plants folks should really focus on.
I've nagged folks about this for a very long time, and I will likely nag you to the grave.
Complacent experts, newbies, test kit freaks, all of you(and myself included).
Poor CO2 reduces growth and is responsible for nearly 95% of all algae related issues. 

Now KH test kit variance is one issue, making a reference standard to compare you KH test to is a very WISE idea to check the accuracy. I've seen many folks have very high CO2 predicted levels, yet fish were fine, but another than has barely 30ppm and the fish are gasping. It cannot be that both are at the same CO2ppm level becaused we would expect to see the same behavior from the fish. Instead we see very wide ranges and impacts on the fish(as well as plants).

So it's much more likely that it is the testing method, rather than anything else.
pH is the best thing as far as accuracy for CO2 measurements using a pH probe and no electrical equipment runnign when the pH is measured(stray current will depress the pH giving false high ppm CO2 levels).

KH test kits have consistency issues (see recent post) and in some places, although rare, non bicarbonate alkalinity exists(recent poster in NM has significant borate alkalinity, desert regions generally).

Addressing this issue by making a reference sample will take care of the KH issue.

The next issue is more interesting for many of of you.
I'd suggested that the venturi DIY reactor I have shown folks on my site is better than any reactor. Well, initially, and perhaps partially true, is the purpging effect of gas build up.
This gas is some O2 and some CO2, but very little "air". 

As the gas is expelled, consistently I see better growth, this is not due to O2. 
So why would a mist of tiny CO2 bubbles vs dissolved CO2 in solution do better for growing plants?

I addressed the O2 issue simply, I used a diffuser disk for CO2(no O2 gas build up occurs).
But that did not do it __alone__.

I wondered why.

So I placed the diffuser disc near similar current like that produced by the venturi reactor after is starts mistuing the gas out the bottom.

Lo and behold, Bam! Excellent similar growth.
Not the kind of so so growth, but pearling like nothing you have ever seen or perhaps only in a very few well run tanks right after a water change. But I'd not done a water change for a week.
I tried it several times on 4 tanks, same result in each tank. Day after day, intense pearling even with fair good current. 

So why would this mist be better than dissolved CO2?

For one thing, it's __pure CO2 gas__, which flows much faster than dissolved CO2 liquid.
The flux rate is much faster with pure CO2 gas than CO2 dissolved in water, so the plants get more CO2 and a more concentrated form.

Some folks may not like the bubbles, some might not like pearling.
But I sure do.

I can say that the venturi effect is one of CO2 now, and not of O2 by using the diffuser disc to rule out O2.

So that just left CO2 and the gas vs dissolved form to consider why one method was better in terms of plant than another.

Both flow and actually having some gas in the tank itself seems to be the key here. 
So those disc are not so bad and neither are the venturi reactors.

You can make a purge loop for external reactors by making a hole 1/2 down and running the air line back to the intake for the power head, caniter filter etc, this will not add bubbles but will reduce the gas build up inside the reactor.

The real issue is having gas bubbles in the tank and putting them where the plants are in that form. 

I think folks should really consider this/these idea/s and try them.
I've had very intense pearling and have over the entire routine time frame, not just for a day or a few days.

Be careful and watch the fish, CO2 levels when doing this, I've not had any fish issues yet. Make sure there is some surface movement. If you use disc, clean them often(monthly). 

For larger tanks, they make 6x1" diffuser stones for about 60$ than can be used set along the bottom back gravel layer so they will not be seen. wwww.aquaticeco.com sells them if interested. 

In any event, this notion of having tiny gas bubbles floating around very dissolved CO2 might solve many folk's problems and improve those who seek better growth.

Nitrogen is an essential element, but only 1.5%, vs 40+ % for Carbon, it is very very wise to focus on this if you seek better growth.

With good CO2 levels, even the wimpy plants do very well(Tonia, ES, Eirocauleon) algae dies, pearling as intense as you have ever seen it day after day will occur.

I think the gas bubbles might also be less of an issue for fish since it's not dissolved into solution also.

The nutrients can be addressed easily by doing EI, so you know there's enough, so all that's left to really focus on is the CO2.

So I have been playing around trying to figuire out a good way to reproduce max CO2 without causing issues for fish, and adding enough for the plants.

The CO2 mist + current seems to be the best method.

This can be done with a reactor or a diffuser stone/disc.

Also, folks using spray bars, turn them vertically, next to the intake and place the disc down near this also. This hides the bar, the disc, intake all in one place. Having the spray bar current blowing along the back side the tank wall seems to give good flow characteristics+ near the disc, the water blows out and away from the intake and circles around to the intake.
Since water is being blown directly away from the intake, this gives optimum mixing.
Since water is being blown directly on top of the difusser, all the bubble mist is being blown all over the tank.

The results are easy to see.

The other issue is not to trust the test kits so much until you see the type of pearling like this, no BBA growth etc, slowly and patiently add more CO2 till you get the pearling and good growth. Basically use the test to get close, then tweak(add more) carefully and slowly.
Do not go overboard, do it slowly and observe the plants/fish. Your test may give you high numbers, but if the fish are fine, then it's okay.
Turing off CO2 at night will help add the margin of safety also. We add CO2 for the plants, not to maintain pH. Some leave it 24/7, but mainly out of convenience rather than methodology. With disc, running them at night can cause issues, anyway, you can save 2-3x the gas by not running it at night. We know fish don't care about the pH change.


Regards, 
Tom Barr

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## seanang168

> i'll vote for reactor! esp those NA external reactor! Just switch from ISTA co2 reactor to NA's and the improvement is significant! never had i seen my HC pearl so much under same condition


Hi may I know what is a NA external reactor? You mean the aquarium shop carries such a reactor using their own brand?

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