# Co2/o2  through same diffuser.?



## kirk (26 Feb 2015)

Hi all, Ive yet to try set up I'm unsure whether non returns can cope with the pressure but here goes. 

On our last set up I used a glass diffuser as a air supply that worked well, the idea is to run the co2 in the day and the air pump on a timer at night to help deliver more of the plants demands. Plus keeping just one tube into the tank and maybe the diffuser may need cleaning less as it's almost goung all the time.  

To keep it as simple as the idea, I want to t off putting in an air pump on the pipe to the diffuser.

Here's a quick sketch.  cheers.


.

I know my air pump will drive the diffuser, my only concearn is....are non return valves up to the job.?


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## EnderUK (26 Feb 2015)

Looks simple enough, the only issue would be leaks with all those connections and as you say the non return valves good qualities should be good to go though.


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## kirk (26 Feb 2015)

I would use the push fit type t peace the ones they use on hydrolics.

The co2 pipe I use is very rigid and has ti be heated to go over anything. So as you mentioned, my only leak concearn would be the actual non returns failing and allowing co2 through the air pump during the day and or O2 going to the regulator at night?.

I've just had a quick look on ebay. There are some brass pushfit non returns quite pricey too.  
One says that the cracking pressure is 7psi, haven't managed to find any stronger yet.


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## Julian (26 Feb 2015)

Someone please correct me if I am wrong, but isn't attaching an air pump to a diffuser is counter productive? I've read that O2 bubbles do not dissolve in water, it's merely the surface agitation they make that causes gas exchange. If what I read is correct, then a diffuser making small O2 bubbles (with little surface agitation) is a bit pointless.

I can't see any faults with the design though.


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## Jose (26 Feb 2015)

I dont think its a good idea mate.
- there is the risk of breaking  or deteriorating your diffuser with your air pump, since it makes a fluctuation in preassure.
- the flow for the oxygen is gonna be much higher than that of the co2 so it should have a diferent design (different difusers). Different flow and different preasure in  the line.

this could work if you were to use a o2 cylinder.


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## ian_m (26 Feb 2015)

Correct it is the surface agitation that adds O2 rather than the considerably smaller surface area of bubbles. This has been extensively proved using radioactive O2 bubbling through adds very little compared to surface.

However your method will produce surface agitation so will increase O2 albeit minor and slowly.


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## Jose (26 Feb 2015)

I dont think this is totally true. Look at your tanks when your plants are pearling. They can get the water to over 100% o2 saturation. So small o2 bubbles do dissolve o2 into the water. Its not necesary though and its easier to have some surface agitation.


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## Andy Thurston (26 Feb 2015)

Strange one this are people confusing o2 with air
I suspect o2 will dissolve in water but air is mainly nitrogen which i suspect wont dissolve in water. It would be interesting to feed a reactor with pure o2 just to see if it does dissolve but i wouldn't want the risk of o2 in the house though


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## Henry (27 Feb 2015)

This may have been disproved, but doesn't the gas pressure required by CO2 didiffusers pretty much wreck any air pump put through them?


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## EnderUK (27 Feb 2015)

Big clown said:


> Strange one this are people confusing o2 with air
> I suspect o2 will dissolve in water but air is mainly nitrogen which i suspect wont dissolve in water. It would be interesting to feed a reactor with pure o2 just to see if it does dissolve but i wouldn't want the risk of o2 in the house though



I think some will dissolve when we're talking about normal air stones just providing water movement we're talking about those airstones with massive bubbles, try getting your CO2 to dissolve with an air stone.


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## kirk (27 Feb 2015)

Thanks all of you. I'm no scientist, I just hate the look of the korilina and air stones.  Maybe ill just remove some more media and increase flow a bit more.
I'm using a 2215 on a 60 ltr so I packed it when I first set up the tank, ill give that a go today.


It's a good healthy debate I've enjoyed reading your posts, nice that people agree or disagree on this subject it's normally distribution or light.


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## ian_m (27 Feb 2015)

The other thing to take into account CO2 is about 40 times more soluble than O2 (see http://www.engineeringtoolbox.com/gases-solubility-water-d_1148.html) so will be easier to get into solution than O2. Also your O2 supply is of course diluted with 80% nitrogen.


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## Jose (27 Feb 2015)

The main thing is that we can push as much air into our tanks as we want because its free, so the method we use for that doesnt need to be very efficient. On the other hand CO2 is  money, so we need to optimize its diffusion with atomizers etc. So its different things that deserve different methods, otherwise one of the two wont reach optimal levels.


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## kirk (27 Feb 2015)

Well I was only trying to kill two birds with one stone/diffuser.   I've removed some media as the filter was due a clean. 
I've removed the hydor as the flow is better,I can now agitate the surface more so it should gass off fine. I'll see tonight, I could be looking into either glass spraybars or a skimmer in the future to keep surface clear of bubbles..  The korilina was a bit much for the plants current wise.  
I think this is the first time ive had co2 micro bubbles making it nearly all the way around the tank.  Cheers all.


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## Saltynay (28 Feb 2015)

Why not swap out your external for an Eheim wet/dry (2217 or 2219) (other brands of filter are available) put the atomiser/diffuser on the inline back to the tank, keep the breather tube relatively short.The eheim "breathing" will ensure maximum O2 levels but will gas off the CO2 which is then re-added after the filter through the inline diffuser. It is at the expense of the CO2 but you will ensure maximum levels for both and save yourself the hassle and cost of plumbing. This appears to be a DIY challenge for the sake of a challenge and as that is gauged on an effort is its own reward is efficiency even a factor?

Also I would avoid the check valve and go with solenoids that way you know the pressure can be withstood and the solenoid will open only when the air pump/ C02 system is active by sharing the same timer. Have a check valve further down the line as your gas enters the tank. So you would need to buy 1 extra solenoid, 1 air pump and a T connector which can withstand the highest pressure.


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## kirk (28 Feb 2015)

I haven't got that type of money to buy a new filter new 17 mm Lillies new tubing. It's only a 45cmx45cmx30 tank probably only 45ltr with all the substrate and rocks.   So no. 

But as for your idea about the solenoids that I hadn't pondered so nice one. I have the pump already.  

Now my flow is more than enough surface is being broken a bit after filter clean and some media removed.

Thanks mate for your input appreciated.


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## kirk (28 Feb 2015)

Henry said:


> This may have been disproved, but doesn't the gas pressure required by CO2 didiffusers pretty much wreck any air pump put through them?


Yes I've disproved it to myself.


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## Saltynay (28 Feb 2015)

Oh you may of took my point the wrong way I assumed you had an external (given the fact you have lilies makes its 99.9% certain now). So just sell your current one and pick up a used 2227 off ebay or aquarists classified or an obliging forum/facebook ect your hoses may even not need to be changed (or included in the sale). Normally used the 2227 goes for around £40 so with the money from your current external you will cover it or maybe have to top up by £10. 2227 uses 16/22mm hoses so your lillies will be compatible with a little heat on the tubing or an adaptor or as I said previously use the same hoses and choose a compatible wet/dry external filter.

PS turns out my eheim number was off by a 1 digit its an 2227 not a 2217 (there is also the same filter but with a heater built in which is a 2327)


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## kirk (28 Feb 2015)

Crickey mate it will be like a spin cycle on a washing machine, why change anything that is working, here my set up I use 12/16 pipes.







  you may just be able to see the flow on surface at the back.  Sorry they are phone pics.


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## Saltynay (28 Feb 2015)

Gorgeous 1ft cube really nice hardscape with the dragon stone.Your right the 2227 would be complete overkill you can reduce the flow at the cost of the impeller but each to their own. The solenoids with a timer is still how I would do it instead of the check valves.


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## kirk (28 Feb 2015)

Thankyou mate and also thankyou for taking the time and getting involved I've enjoyed the chat.


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