# Best Way To Inject CO2 In A 400l Sump'd Set Up



## jagillham (12 May 2015)

I am looking to replace my ceramic diffuser as it no longer 'mists', but just blows bubbles. This is despite being bleach cleaned a few weeks back which did fix the issue for while.

The tank is 400l, with around a 60l sump which returns to the tank via a bulkhead approx 10cm under the surface. 

What would the best way to disolve the CO2 into the system be? I can do it either in the sump, in line or in the tank - I don't mind.


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## RossMartin (13 May 2015)

Hmmm if it were me i would perhaps run a large reactor that returns the CO2 enriched water into the sump just before the return pump. So i would have a pump that takes sump water into the reactor, mixes with the CO2 and then returns back into the sump.  

This thread will help. http://www.ukaps.org/forum/threads/high-flow-diy-reactor-now-with-video.23337/


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## Jose (13 May 2015)

It depends how powerful your pump is. If you dont want to loose any flow or dont want to put more pumps then I'd go for an inline atomizer. If you could put as much flow as needed then a mazzei venturi diffuser would be best but needs very powerful and special pumps. Reactors might leave you flowless, but its another option.


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## jagillham (13 May 2015)

The return is a Eheim Compact 3000+ if that's any help? I have a powerhead in the tank itself, so the flow from the filter isn't as important as it might be.

I'll take a look at those links


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## RossMartin (13 May 2015)

My thinking was to use a separate pump just for the reactor to move sump water through it, like a closed loop system. That way nothing is lost from the return. A small Eheim compact would be more than adequate!!


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## jagillham (14 May 2015)

Any ideas on the size of pump / suggestions? Would potentially have the rejig the sump to add it. Currently the return and two heaters are in the last chamber - so getting a bit crowded.


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## Jose (14 May 2015)

Its a 5000 l/h pump. Its not bad at all. It depends also if its placed a long distance under the outflow. So you have to decide between a reactor and an atomizer. They both have their pros and cons. I dont really like reactors too much. You can place the atomizer on the intake of the pump and have all the co2 dissolved, but then youd need your sump sealed I guess. The simplest way would be an atomizer on the outlet of the pump. Youll get a very fine mist in your tank which shouldnt be too bad. 

The reactor will dissolve 100% possibly but youll need to do a lot of tweaking to get it working well. And you need a proper length reactor. 

I guess the main question is: Do you mind using a bit more co2? If you arent to tight with co2 then an atomizer might be your choice. Otherwise you need a reactor.


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## Christos Ioannou (14 May 2015)

Hi just yesterday I had a go with Rex Crigg's diy reactor to replace an inline atomiser that was too fragile for my hands (co2 inlet broke). Day1 results I am happy since I had no loss in flow (water from spraybar still hits front glass) and also a pH drop of 1 unit in 1 hour with less co2 than that used with the (clogged?) atomiser. Total cost about 20eur.


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## jagillham (14 May 2015)

What kind of tweaking would be required on the reactor CO2 waste isn't too much of an issue really. Considering the amount reaching the surface with the ceramic defuser at the moment.


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## foxfish (15 May 2015)

If you don't mind a mist in the display then the simple method would be to place the CO2 line directly in front of the sump return pump ... Job done!
The next step forward to get an even better dissolve rate would be to purchase a needle wheel return pump, as that will produce an even finer mist.... Or for the same effect you could place a UP atomizer right in front of your pump suction inlet.
For a mist free display you can use a 20" reactor as described in my signature link.... however no matter what method you employ, expect to use a lot of gas! A 400lt tank with a sump will need a big supply of CO2.

I ran a big tank for many years by using a simple ceramic diffuser placed in front of my return pump. I found that 250ml plastic drinks bottle would fit over the pump inlet so I cut of the bottom of the bottle and placed the diffuser in the bottle. This simple method worked trouble free for years......


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## jagillham (15 May 2015)

I've had a look at your link before when mentioned earlier up the thread, seems like a good idea. Do you think running the sump outflow through the reactor straight into the tank return would work? Or is it preferable to run the reactor back into the last chamber of the sump.

Are there any issues with the reactor (or reactors in general)? I was wondering if the CO2 did not dissolve fast enough if it would fill with gas and then either crack / explode or create an air lock stopping the water flow?


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## Jose (15 May 2015)

jagillham said:


> Are there any issues with the reactor (or reactors in general)? I was wondering if the CO2 did not dissolve fast enough if it would fill with gas and then either crack / explode or create an air lock stopping the water flow?



This is the kind of tweaking I was talking about. Basically making sure that co2 bubbles dont scape (at least big ones), making sure flow is good, and making sure your reactor has a good design as to dissolve the ammount of co2 you want (this depends on the pump as well). Then you also have to get your offgassing right so that co2 levels dont keep climbing forever.


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## foxfish (15 May 2015)

The main benefit of a reactor is to avoid a mist in the tank, if that is your goal then a 20" high  reactor with a adjustable flow pump will work very well.
There are many other forms of reactor that will also work, the most basic designs are simple tubes with an inlet & outlet at either end. The longer the pipe the less likely to get any stray bubbles in the display. However there are no commercial reactors of that nature available (that I know of) so you are in the realms of DIY.
Due to the overflow required to feed a sump, there will be a lot of degasing but this also allows for a very stable level of CO2. That is the price you pay for having a sump!
For the shear low maintenance aspect a needle wheel pump cant be beaten.


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## Jose (15 May 2015)

foxfish, Do you reckon that a needle pump is as efficient as an inline atomizer or more? I dont have experience with them. i guess they have to be DIYed?


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## foxfish (15 May 2015)

I don't know to be honest but on a big tank where a lot of gas is required you would probably need two UPs against one pump.
A few years back there were many NW pumps available due to their success powering protein skimmers, I am not up to speed as to what is available at the moment but you don't have to look far to find one http://www.charterhouse-aquatics.co...EXr2FBZEUIuT70RI_pVlk3FXXFlyk-nGF0aAmxZ8P8HAQ


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## ian_m (15 May 2015)

Of course you can make your own needle wheel pump, Google for "diy needle wheel pump" and see what I mean.

One word of warning I did get from reading some oh these is that they can be noisy unless submerged in a sump, so DIY are not suitable for running externally in a CO2 loop.


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## jagillham (15 May 2015)

Anybody have any thoughts on something like this for a reactor...?

http://www.ebay.co.uk/itm/CO2-Exter...394?pt=LH_DefaultDomain_3&hash=item20fb309072


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## foxfish (15 May 2015)

Yes, my thoughts are you will need one about 10 x the size 
Ian, you are right but a DIY job wont do half as  good a job as a moulded wheel & you tend to loose a lot of flow.


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## kirk (15 May 2015)

Utter pants....are my thoughts, I've had one in the forsales for a while, even offers, tells you peoples thoughts 

Some people love them i think they are a pain. 

Someone on here has build one from an ro unit canister, I thought about doing this a while ago but never did. They have done a great job. 
I think that would be the way drop an diffuser inside or something similar. 
You have a lot of water.


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## jagillham (15 May 2015)

Not a fan then! 

I know my tank is not small one, but at 400l its by no means a monster.

Why does the reactor need to be quite so tall?


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## jagillham (15 May 2015)

Read the whole thread now... is this any good for the housing?

http://www.ebay.co.uk/itm/WATER-FIL...588?pt=LH_DefaultDomain_3&hash=item19feec227c


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## foxfish (16 May 2015)

Yes, that looks good.....very cheap price!


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## jagillham (16 May 2015)

Glad you think so... wonder if the wife will think £25 OK for a plastic tube !

Not sure if this one any better / different? Same price...

http://www.ebay.co.uk/itm/20-WATER-...t=LH_DefaultDomain_3&var=&hash=item463a6f6786


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