Co2 tweaks.

Discussion in 'Carbon Dioxide (CO2)' started by Garuf, 8 Sep 2008.

  1. Garuf

    Garuf Member

    Messages:
    4,959
    Location:
    Leeds.
    Hello, I recently have come down with co2 and flow related algae, bba and clado. In an attempt to up the co2 I have started turning my co2 on earlier (2.5 hours before lights on) and I've noticed no real change, am I missing something or is it actually not possible to significantly increase co2 levels and stability of co2 in this way?
    Also, I turn the co2 off 1 hour before lights off, is it feasible to increase this time period or should I be doing this at all?
    Co2 has always been a stumbling block and I'm hoping to finally crack it.
     
  2. Ed Seeley

    Ed Seeley Member

    Messages:
    3,262
    Location:
    Nottingham
    CO2 reaches an equilibrium level according to how much you are adding, how efficient your diffusion and circulation is against how much is being lost through CO2 coming out of solution at the water's surface (as function of the surface area, flow and surface disturbance among other things) and how much is being used by the plants (and water chemistry). However long it takes to get there will depend on many factors but starting to add it earlier will not make it more stable, unless it was taking 2.5 hours to reach that equilibrium! I would imagine that you're now simply reaching the CO2 equilibrium before lights on earlier.

    I kinda think that, except on huge tanks maybe, if it takes more than an hour to get up to the CO2 level you want before lights out that you're probably not going to keep the CO2 level stable when the lights come on and start photosynthesizing.
     
  3. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Messages:
    8,953
    Location:
    Chicago, USA
    Yes, agreed. Your ON/OFF sequence is fine so you need to look at upping the injection rate and/or upping the flow. Lighting levels are an issue as well so that may need to be lowered if the other factors cannot be adjusted.

    Cheers,
     
  4. Garuf

    Garuf Member

    Messages:
    4,959
    Location:
    Leeds.
    I see, I'll increase the injection rate I was thinking that because the co2 is coming on earlier it would reach equilibrium before the lights on then it would remain stable at this higher level but this seems to not be the case so I shall just increase the injection rate.

    Does the pressure in which the co2 enter the water have any effect? For example when I run the co2 at 2bar rather than one I seem to get more fine mist than when on 1bar but with less bubbles going through the bubble counter.
     
  5. Garuf

    Garuf Member

    Messages:
    4,959
    Location:
    Leeds.
    I totally reset my co2 rig, in contemplation to what Ed said about the long start up time and cut it back to a single hour, at the same time I upped the bubble rate by nearly double. The co2 still goes off an hour before lights. The drop checker is now darker when lights come on but I'm slowly upping the levels until I gas everything. Which may be sooner than I think... See the thing is, when the lights are on the fish are happy healthy and active, lights go off and come about 7am everything is gasping at the surface and my drop checker is still the same shade of yellowy green as when the lights went off. I checked that the co2 wasn't set to "random" on the timers as it has been before (albeit leading to some algae issue) Before everything was fine but now lights off means fish to the surface.
    Anyone got any ideas on what it could be?
     
  6. Egmel

    Egmel Member

    Messages:
    724
    Location:
    Guildford, Surrey, UK
    I don't run pressurised CO2 so take this with a pinch of salt, but it sounds like you could do with more surface movement at night when everything is respiring but not photosynthesising. Therefore O2 -> CO2 but little to no CO2 -> O2.
     
  7. a1Matt

    a1Matt Member

    Messages:
    2,498
    Location:
    Bromley

    That sounds spot on to me.

    I have experimented with combinations of different CO2 levels \ different spray bar heights in my tank. My findings were that if I have minimal surface disruption then the drop checker is still the same colour the next morning as it was at lights out the night before. (With a lot of surface movement it was harder to get the CO2 levels up and the drop checker colour varied a lot at different times.)
     
  8. Garuf

    Garuf Member

    Messages:
    4,959
    Location:
    Leeds.
    Hmm could be, I use silly pipes and the surface agitation is minimal, Ill raise it up and see if It makes a difference.
     
  9. a1Matt

    a1Matt Member

    Messages:
    2,498
    Location:
    Bromley
    In my tank it is quite a fine line between not enough movement (top of the tank gets a little bit scummy), and too much (messes up my CO2 levels).

    To get to a point I am happy with involved playing about a lot with my spray bar - different heights, angles, and lengths of the bar itself. I appreciate you are using lilly pipes, I guess I just wanted to stress that little changes can make quite noticeable differences.

    Anyways, good luck with it and enjoy the process of trying different things out :)
     
  10. GreenNeedle

    GreenNeedle Member

    Messages:
    2,706
    Location:
    Lincoln UK
    Could you not leave the injection rate high as it now is, and leave the shorter pre lights injection period but lengthen the pre light switch off?

    i.e. on 1 hour pre lights on and off 3-4 hours pre lights off. I think Ceg runs his something like that.

    AC
     
  11. Ed Seeley

    Ed Seeley Member

    Messages:
    3,262
    Location:
    Nottingham
    Agree completely with Andy. Turn it off earlier. Do bear in mind that a drop checker has a delay in the colour change of an hour or so so, in theory, if your DC starts turning darker an hour after lights out then it's just timed right! Personally I'd use the fish's responses as a guide in your case.
     

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