# Best way of dissolving CO2?



## Crossocheilus (17 Aug 2014)

I am wondering what is generally considered the best way to dissolve CO2 in the aquarium. I know a lot of people use inline atomisers, but it seems reactors, if made properly can achieve 100% dissolution. However these reactors are often large, difficult to perfect and can drastically reduce the flow output of external canister filters. So what method gives the best dissolution, but is also practical?


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## Vazkez (17 Aug 2014)

Hello there 

as I was advice few days ago I say inline atomizer but hooked on intel (as far from the filter as you can) and not outlet. The differences are just stunning  

I used to use the reactor as well but thats hit your flow very hard,

Vazz


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## Sacha (17 Aug 2014)

Are there any filters that you can use an atomizer on the inlet with? Without cavitation?


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## Crossocheilus (17 Aug 2014)

My only problem with the atomizer on intake pipe of the filter is that it will require very frequent cleaning.[DOUBLEPOST=1408300231][/DOUBLEPOST]Dunno Sacha, I'll probably be using a jbl e1501 greenline if anyone knows how that copes with cavitation.


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## foxfish (17 Aug 2014)

A lot depends on the amount of co2 that your tank requires?


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## Vazkez (17 Aug 2014)

Sacha said:


> Are there any filters that you can use an atomizer on the inlet with? Without cavitation?



As you know I am using the APS canster and no problems so far. I removed most of the media tho.




Crossocheilus said:


> My only problem with the atomizer on intake pipe of the filter is that it will require very frequent cleaning.



I put sponge at start of the intel so hope thats helps a bit


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## Crossocheilus (17 Aug 2014)

Ok, well it will be 90 x 45 x 45cm so that's 180L and on start up using 2 39w T5s then possibly increasing to 3 tubes. So 180L medium-high light, EI dosing, want good growth preferably without the algae


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## foxfish (17 Aug 2014)

Well if you don't want algae then you need lots of C02 and not so much light!
You can look at my signature link for a high flow reactor design but you might, need a 20" version for 3 x T5s.


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## Crossocheilus (17 Aug 2014)

Yeah I've seen your reactor Foxfish and it looks good, however I did notice a lot of the people who attempted it struggled to dial it in, the balance between the bottle shape, co2 rate and flow rate seemed tricky. I know there won't be a perfect answer to co2 dissolution but your design, although effective once dialled in seems rather difficult to perfect and requires building + sourcing parts.


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## foxfish (17 Aug 2014)

Fair comment...
In that case you are asking a difficult question!
If there was an ultimate method everybody would be using it!
20" tall reactors work well, very large externals with little media work well as do several of the micro bubble diffusers but, there is no one ultimate method that suits all .... as yet.....


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## Crossocheilus (17 Aug 2014)

Yes I suppose I am asking the question we all want the answer to, but reactors,  if done well are generally better than atomizers? If so I suppose I've got several weeks before I get my tank so a bit of time to fiddle with a diy reactor. Thanks anyway Foxfish


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## foxfish (17 Aug 2014)

No, reactors are not better that micro bubble devices, just two different methods.
It has been said that atomisers allow easier uptake for the plants but you have to suffer the visible bubbles.
Reactors don't produce the mist but are larger units & require setting up or fiddling with to get the best from them.
Large reactors are pretty fail safe but need to be outside of the tank cabinet.


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## Crossocheilus (17 Aug 2014)

Hmm well I thought plenty of people said they use less co2 with a reactor therefore dissolution is higher. By me saying "better" I suppose it was fairly ambiguous. I meant most efficient (least co2 required). I assume dissolved co2 is dissolved co2, with my gcse knowledge of plant biology I see no way in which micro bubbles are easier to absorb than fully dissolved co2. If that's completely wrong do tell me, its just what I would expect.


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## foxfish (17 Aug 2014)

Micro bubbles offer direct contact of C02 not dissolved C02 to the plants surface, however that is just what you can read, not what I actually  know!
Personally I don't see much significance regarding any saving in C02 between the two methods.
I am not really a fan of micro bubbles or the high working pressure required to operate inline atomisers but I have used them successfully.


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## Crossocheilus (17 Aug 2014)

Well it sounds like an atomizer would be a perfectly good place to start. If I get fed up of the bubbles I can look into alternatives, thanks for all the advice, you clearly know your stuff Foxfish


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## Vazkez (17 Aug 2014)

Crossocheilus said:


> Well it sounds like an atomizer would be a perfectly good place to start



Just one plus when you hook it to intel >>> your tank no longer looks like botlle of Coke  Just saying [DOUBLEPOST=1408306772][/DOUBLEPOST]Actually thats plus for reactors as well


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## foxfish (17 Aug 2014)

Connecting to inlet will not suit everyone, it depends on the amount of C02 your tank requires compared to the filter size, design, amount of media  & flow rate.
The device needs to be serviced regularly to avoid dirt accumulating but the main disadvantage is an invisible build up of Co2 causing the filter to burp & purge pockets of stored gas into the tank. 
It does work very well for some people but many others have issues!


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## Crossocheilus (17 Aug 2014)

I'll give that a go too, thanks Vazkez


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## X3NiTH (17 Aug 2014)

My setup is slightly different to the design from Foxfish. I use an inline atomiser on my canister outlet and I have plumbed in a large 20" reactor after it. My down tube is just 40mm piping jammed onto the housing lid outlet and siliconed in place with a couple of close fitting sponges on the outside of it. I've used Eheim double taps so I can isolate the unit for cleaning.

https://farm8.staticflickr.com/7262/13903132322_16f1cf3da6_b.jpg

Cleaning is done by isolating the unit and letting out some water and holding it in my arms to give it a shake from side to side to slosh the water around inside dislodging any debris build up in the sponges (it's not actually as heavy as it looks), it's then just a case of emptying by running clean water through in the reverse direction so all the debris gets flushed up the down pipe and out. Fill with clean water and reconnect to the system, easy! I only need to do this every few months, I dare say I could do without the sponges but I feel the bottom sponge at least helps trap the co2 as it emerges from the down pipe slowing it down enough to let it dissolve in the water, there are no bubbles above the bottom sponge but bubbles do emerge from the down pipe.

https://farm4.staticflickr.com/3779/13903153192_194f439d02_z.jpg

100% dissolution, no gas build up when running and if there is reduction in flow it's minimal.


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## Crossocheilus (18 Aug 2014)

The use of sponges seems a good idea, perhaps allowing the unit to be made smaller and simpler, but achieving the same result, the same principle can be used by running co2 into the filter as mentioned above. Thanks x3nith for another great idea, I'll have to just experiment until I find a solution that I am happy with.


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## Martin in Holland (18 Aug 2014)

Maybe if you have a pre-filter, you could get the inline diffuser between that and your filter. This would help with the constant cleaning of the diffuser and still get the filter as a reactor.


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## Crossocheilus (18 Aug 2014)

Again a good idea, thanks Martin.


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## Sacha (18 Aug 2014)

I hate the 'champagne' look that my tank has taken on recently. I may try to connect the atomizer to the filter inlet hose. I am concerned about cavitation, because it's not always noticeable. If Co2 builds up around the impeller alone, the impeller could run dry, and you wouldn't realise until it had burnt out.


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## ddam19 (18 Aug 2014)

What about using a cheap external filter for Co2 (i.e no media) and another as a filter?

Just an ideal as i just use diffuser as filter is built in.


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## X3NiTH (18 Aug 2014)

Sacha said:


> If Co2 builds up around the impeller alone, the impeller could run dry, and you wouldn't realise until it had burnt out.



Which is why I built my reactor the way I did, minimal maintenance and zero gas build up when in use. At first it can be a bit of a pig to prime if there's air in the down tube when it's all plumbed in to the canister but I found a tilt to horizontal of the unit sorts that out immediately. After cleaning the unit I now always run it on a closed line using an Eheim pump and depress the button on top to release any air in the unit and then lock the taps when it's full and instal back in place.


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## Crossocheilus (18 Aug 2014)

Those filter housings are expensive though, I just recently discovered a huge collection of plumbing supplies in the POND section of my local Maidenhead Aquatics and so could build a reactor like Alastair's, and use a sponge to trap the last bubbles. However it does seem the biggest problem with all of these reactors is the priming, for Alastair's style a bleed valve may be needed.


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## terry82517 (18 Aug 2014)

Those pesky last bubbles are the bane of my life rite now lol.


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## Crossocheilus (18 Aug 2014)

Rubbish drawing but you get the idea…

One big problem with this would be it would be VERY difficult to clean, the hose tails would be unscrew-able but cleaning round those corners virtually impossible, I decided to have no bleed valve and so i'd just fill up with water to install (using double taps). This hasn't really been thought through its just a preliminary idea.[DOUBLEPOST=1408374646][/DOUBLEPOST]I think X3NiTH's design would be easiest but perhaps expensive.


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## X3NiTH (18 Aug 2014)

It's not that expensive when compared to burning out the motor on a pump. You can get the 20" housings online for £25 (possibly slimline 8" diameter 3/4"BSP port opaque unit), my clear Watts 20" (10" diameter head with 1" BSP ports) was about £70 the two double taps were about £40 and the elbowed outlets were only a few quid each, but my Canister filter was £300 and I'd rather not risk torching it. But I didn't necessarily build it to minimise risk I did it to get crystal water and 100% co2 dissolution.

The design is not mine, it's the culmination of many ideas that evolved over a very long thread over on TheBarrReport.


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## nebula (21 Aug 2014)

hi ukaps,

this will be my first post here. i'm running a 60gal planted tank, which is about 5 months old now and it was low-tech during this period. now i had the chance to add a  high-pressure co2 system to the mix, so since that few days i'm playing around with the placement of the ceramic diffuser.
as the co2 system was lent me, i have to live with what i've got  so currently there's no possibility to change to atomiser or reactor.

the problem is coming from the fact that the tank is not paralell to the wall, it is perpendicular to it, so it is not that nice to put the diffuser at the opposite end as where the lily is placed - the tubes hanging around would ruin the view.

therefore i was thinking i'll put the diffuser close to the glass inlet - the filter is a 13gal plastic barrel with an eheim compact+ 2000 pump, running at max - so the flow would catch most bubbles and take them into the filter where they would break apart and dissolve.

i've posted this idea onto the greenaqua boards [i'm hungarian], but i've had the response that it would kill the bacteria in the filter.
and now i see that here some of you had placed the inline diffuser into the inlet tube of the filter. so the question is: is it a good idea to let the filter do the work of a reactor, or it will really reduce bacteria? did anyone who has the diffuser in the inlet have any negative effect on filtering?

thanks in advance


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## Crossocheilus (21 Aug 2014)

Well with co2 going into the filter the oxygen levels,  oxygen being vital for the bacteria that convert ammonia-nitrite-nitrate, will be the same as without co2 and the co2 concentration should be similar to that of the rest of the tank. Anyway, in planted tanks the filter is only one of many sources of filtration,  there are beneficial bacteria in the substrate and the plants use up nitrogenous waste. So as long as the gas doesn't build up in the filter, damaging the pump, it should be fine.


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## nebula (21 Aug 2014)

thanks, this is the same as i've thought...


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## Crossocheilus (21 Aug 2014)

I'm glad I could help. Oh and welcome to ukaps!


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## EnderUK (21 Aug 2014)

I was suffering from poor flow with my reactor, I took out the impeller, shortern some of my tubing and added a nano powerhead. Job done.


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