CO2 Diffusion

Discussion in 'Carbon Dioxide (CO2)' started by Aeropars, 24 Apr 2008.

  1. Aeropars

    Aeropars Member

    Messages:
    779
    Location:
    Leicester
    Firstly, here's my hardware:

    The CO2 reactor:
    [​IMG]

    The filter:
    [​IMG]

    It appears that I could be wasting a lot of CO2 using my current configuration as I'm getting gas spurts coming out the filter outlet. The reactor is advertised as being suitable up to 1000 liters and I'm using it on a 180 liter so i would expect it to be highly efficient for this amount. The filter is capable of about 1400 lph which is about whats recommended on this filter.

    Having met Dan this week and saw how little CO2 he gets through, its opened my eyes that I'm not running efficiently.

    My current 2kg bottle of CO2 has lasted for about a month while Dan can stretch his for 4 months while maintaining 30ppm. He is using a ceramic reactor into his external filter.

    My current configuration is as follows:

    Filter inlet > Filter input > Filter output > CO2 Reactor > Filter Outlet

    Any ideas on how I can get better diffusion?
     
  2. milla

    milla Member

    Messages:
    241
    Location:
    Leeds
    I have this reactor on a 180L tank using 600g bottles which last 4-6 weeks (on 8hrs a day) @ approx 3bubbles per sec.
    I never see gas spurts. Filter is 1200lph
    Probably a daft question but you have got the water flow going the correct way through the reactor ?
    The water comes in at the top on this reactor with the gas coming in at the bottom against the water flow.
     
  3. Aeropars

    Aeropars Member

    Messages:
    779
    Location:
    Leicester
    I beleive so, input at the top, output at the bottom so the gas has to fight against the current as it rises.

    Incidentally, is your reactor perfectly verticle? Mine is about 2mm off but wondered if this could be the cause.
     
  4. beeky

    beeky Member

    Messages:
    879
    Location:
    Chippenham, Wiltshire
    I don't understand why you'd be getting gas spurts unless the gas is going into the inlet of the filter, but from what you said you have the gas being added on the way out.

    Interesting point about the water flow. I've got a reactor that's very similar and about to be plumbed in, so very good timing!
     
  5. Aeropars

    Aeropars Member

    Messages:
    779
    Location:
    Leicester
    I would have said gas suprts would be less likely if the co2 reactor was on the filter input site as any gas escaping would have more time and turbulence to disolve in the water. Thats what some people do with their ceramic reactors deliberatly putting them beneath the filter inlet.
     
  6. LondonDragon

    LondonDragon Administrator Staff Member

    Messages:
    10,283
    Location:
    London
    I was also thinking of getting one of those reactors, are they really better than a ceramic diffusor inside the tank?
    thanks
     
  7. Dan Crawford

    Dan Crawford Founder Staff Member

    Messages:
    3,266
    Location:
    Daventry, Northants
    Could these spurts or burps be just a build up of oxygen and other gasses which in a situation without the reactor in the line of flow would just be expelled into the aquarium without a noticeable burp? A lot of people who have their diffuser placed just below the filter inlet see this happening (in this case it's a build up of CO2 within the external)
    Just a thought.
     
  8. Aeropars

    Aeropars Member

    Messages:
    779
    Location:
    Leicester
    I dont think so as I've turned the CO2 down a little and it stops it although I'm not sure how much effect this will have on the amount of CO2 in the water.
     
  9. Aeropars

    Aeropars Member

    Messages:
    779
    Location:
    Leicester
    Well, I turned the CO2 down a little and i'm still getting spurts coming out of the filter outlet. Really frustrating as i'm certain i'm wasting a lot of CO2 with it. Anyone got any further suggestions?
     
  10. Aeropars

    Aeropars Member

    Messages:
    779
    Location:
    Leicester
    Not wanting to sound like a moaning Grandad but it would be benificial to create your own thread. It stops threads getting hijacked and dtreacting from the original subject.

    I've split the thread to avoid any problems. Ed.

    Back to my problem, I noticed yesterday that there was a buildup of co2 right at the bottom of the filter which i pre4sume is stopping the co2 from rising against the current to the top of the reactor. Does anyone know how to clean these things?
     
  11. milla

    milla Member

    Messages:
    241
    Location:
    Leeds
    Is fairly easy to clean. The top unscrews so you can remove the green net and rinse through. :D
     
  12. Aeropars

    Aeropars Member

    Messages:
    779
    Location:
    Leicester
    See, I never knew that! James just let the cat out the bay on a PM i sent him :D

    I'll have to give that a go then!
     
  13. Aeropars

    Aeropars Member

    Messages:
    779
    Location:
    Leicester
    Well I happened to get my 500gram JBL bottle on the go about 2 weeks ago and today it ran out.

    I really do think there is something wrong with the diffusion happening in the reactor as I would expect the CO2 to last at least a month on a 500 gram.

    I'm still getting loads of constant little bubbles coming out the filter outlet which i'm pretty sure is CO2 being wasted.

    Do you think by adding more mesh to the reactor that this will help?
     
  14. Aeropars

    Aeropars Member

    Messages:
    779
    Location:
    Leicester
    I had a reply from the company who sold it to me and he said i need to reduce the flow! Highly miffed at this response as this is advertised as suitable for 1000l tanks! You would need even more power filtration on a tank that size so would cause this problem even worse!!

    Any thoughts guys?
     
  15. milla

    milla Member

    Messages:
    241
    Location:
    Leeds
    I was under the impression that the 1000L refered to a flow through rate of upto 1000L/ph not the size of tank. :)
     
  16. ulster exile

    ulster exile Member

    Messages:
    353
    Location:
    Birmingham, UK
    Ditto, its suitability refers to the filter's flow rate. I would have thought that if the CO2 is effectively being 'stuck' at the bottom near the inttake, this is an indication that the water flowing from the top is too powerful to let the reaktor do its job.
     
  17. Aeropars

    Aeropars Member

    Messages:
    779
    Location:
    Leicester
    Well, I cant see the gas being stuck at the bottom although it is difficult to see.

    I'm half tempted to reverse the inlet and outlet so that the bubbles get churned up in the filter as well.
     
  18. JamesC

    JamesC Member

    Messages:
    1,276
    Location:
    Bexley, Kent
    The reactor is for a 1000 litre tank. I would be amazed if your filter is too powerful as I have a more powerful one and I'd say it was really only just powerful enough to work the reactor (Eheim 2028 btw). CO2 dissolves so quickly it is unlikely that these bubbles are CO2, but more likely oxygen or nitrogen. If your filter isn't providing enough flow through the reactor you tend to get a gas buildup at the top which casuses a lot of splashing and more gas (O2?) to come out of solution. The splashing causes small bubbles that come out of the bottom of the reactor and into the tank.

    Having a gas buildup does decrease the efficiency of the reactor but not to a great extent IMHO. I have a 200 litre tank and it goes through 6.35kg of CO2 in 6 months which equates to about 500g every two weeks.

    Before I had the Eheim I used a Rena XP2 which I replaced as it wasn't up to the job. I used to get the daily build up of gas at the top of the reactor and small bubbles coming into the tank and also used to think that perhaps it was CO2. What I did to test if it was or not, was to pump in loads more CO2 very quickly into the reactor to add a couple of inches to the height of the gas buildup. Then turn the CO2 off and watch what happened. What I saw was that within several seconds the gas level went straight back to where it was before adding the extra CO2 demonstrating to me that CO2 was still being readily dissolved and that the remaining gas most likely wasn't CO2.

    James
     
  19. a1Matt

    a1Matt Member

    Messages:
    2,518
    Location:
    Bromley
    You could easily add a venturi loop to your existing reactor. This would then reduce any gas build ups as they occur (be they spurious gases or C02), allowing your reactor to run at full efficiency (however good that may be! )

    The venturi is Tom Barr's design and he has details on his website for both internal and external versions:

    Internal:
    http://www.barrreport.com/estimative-in ... esign.html
    External:
    http://www.barrreport.com/articles/3444 ... actor.html

    I DIY'ed an internal one (out of an old gravel cleaner and spare tubing I had and a £5 pump off ebay) and it works well. (FWIW at apprx 0.5-.75bps my 2kg bottle lasts 6 months or so.)

    It took me 15 minute to make and hell of a lot longer to fully undertand how it works! :lol:
     
  20. Aeropars

    Aeropars Member

    Messages:
    779
    Location:
    Leicester
    Whats Venturi?!
     

Share This Page

Facebook Page
Twitter Page
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice