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Mixing Co2 with water

Always Broke

Member
Joined
28 Feb 2010
Messages
226
Location
Penryn Cornwall
So we all inject this stuff into out tanks. Some use inline reactors and others use diffusers in the tank.
How can we increase the dissolved Co2 content in the water. For instance if the Co2 is in contact with the water in a confined area for a long period of time will the water take up more of the Co2. What I want to do it try and use the Co2 more effectively. Most of it from what I can see just goes back into the atmosphere.

Simon
 
Hi Simon
Always Broke said:
How can we increase the dissolved Co2 content in the water.
That question, my man, is the holy grail :lol:
Always Broke said:
For instance if the Co2 is in contact with the water in a confined area for a long period of time will the water take up more of the Co2.
Well that's the theory anyway.
Where I saw this with my own eyes was my very first CO2 set up. I use a JBL system, and after breaking 2 glass diffusers :oops: I needed to get some CO2 in the tank a bit lively, so being a weekend, I had to dig out the JBL box and in it was one of the JBL spiral diffusers. With this type the bubble enters at the bottom and works it's way up the spiral. When the bubble starts it's journey it was around 3mm diameter and by the time it got to the top it was less than 1mm diameter. So a lot of the CO2 had obviously diffused into the water.
Nowadays I'm using the Aquamedic 1000 in line reactor and the contact time is greater, therefore more, if not most, of the CO2 gets dissolved .
I only get the odd small bubble coming out of the spraybar now and again so most of it must be diffused. Much more efficient than the spiral type, and the added bonus is you don't end up staring at a tank full of micro bubbles that you get with diffusers and some in line reactors :D .
So from my own observations I would say that the contact time is the key.
Now we've got that bit sussed, next on the list is distribution.
You can diffuse all the CO2 you like, but getting it distributed evenly around the tank...........well that's another matter altogether (and I've got the tee shirt :lol:. Been there, done that, got it wrong :oops: ).
 
Yeah, I agree. That's just life in the fast lane unfortunately. To get better CO2 you have to introduce a different technology which uses the principle of a carburettor and which reduces the diameter of the CO2 bubbles under high velocity. The small bubbles actually form a "mist" and when they make contact with the plant leaves they are assimilated much easier than when they are dissolved in water. These are referred to as Mazzei injectors, but that's a project for another day. Mazzei is an industrial pneumatic company and their products are used in the petrochemical and medical fields. The techniques and equipment are commonplace in the USA but are virtually unknown in the UK.

The best you can hope to do with the rather crude diffusers is to saturate your sump using high injection rates, or, for those without sumps, to use external reactors which maximize contact time of water and gas.

Cheers,
 
Bobtastic said:
I am looking to get a Aqua Medic 1000 reactor (or something similar) to maximise the disolved Co2 and then I'm going to add another power head to help move the freshly disolved Co2 around the tank better.

After a major leak on my DIY reactor and an Aquamedic 1000 turning up cheap im now using it. I get NO co2 from my bar at all.

I have mine VERY close to the filter soo its got to travel a further 2.5m once its out of the reactor.

Im also disolving enough to do a 500l tank and i think im a little higher than the normal 30ppm it is a capable reactor.
 
Hi all,
"to use external reactors which maximize contact time of water and gas."
&
"which reduces the diameter of the CO2 bubbles under high velocity. The small bubbles actually form a "mist" and when they make contact with the plant leaves they are assimilated much easier than when they are dissolved in water."
As suggested by Clive for maximum efficiency you need to combine long "residence time", with very small bubbles. Because of the surface area to volume ratio small bubbles dissolve much more quickly than large bubbles, (this is the difference in diameter cubed). The plus side is that CO2 is much more soluble than O2. For O2 injection the waste water industry has recently developed micro-bubble production using EPDM membrane diffusers.

cheers Darrel
 
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