Oxygenation of water and CO2 infusion

Discussion in 'General Planted Tank Discussions' started by nrwatson, 18 Sep 2008.

  1. nrwatson

    nrwatson Member

    Messages:
    29
    I am trying to get my head around this
    I have a 180l tank with a jbl co2 system and a JBL PROFLORA CO2 pH Control 12 V this is keeping my pH at 7.00
    Therefore I shouldnt need to turn off my CO2 at night but if I dont then my fish are struggling in the morning the rasbors are all at the surface struggling and the cardinals loose their colour the pH hasnt changed both meter and drop checker colour but obviously with out plants producing 02 the fish are struggling
    I have now aerated the tank which I am leaving on all day and night Lost a Discus because of lack of O2
    Any thoughts ideas would be helpful

    The Tank is starting to get algae when previously not a problem

    The set up is
    substrate base Flora base I put in an undergravel cable and have planted out my aqarium
    Rotala rotundiflora
    Microsorum pteropus Windelov
    Vallisneria spiralis TigerHygrophilia corymbosa Siamensis 53B
    Cryptocoryne selection XI
    Echinodorus sunlight mad
    I think utricularia graminifolia
    Taxiphyllum barbieri
    I have a 180L Fluval vision tank
    A Einheim Jaeegar heater
    two Einheim filters external 2217 and a pro3e
    and fluval light to be upgraded to Arcadia Plant Pro T5 34" - 850mm - 39Watts
    I have the JBL CO2 system and pH controller
     
  2. LondonDragon

    LondonDragon Administrator Staff Member

    Messages:
    10,271
    Location:
    London
    From what I have read many times I would get rid of the PH Controler, run the CO2 two hours before lights on and turn it off two hours before lights out and run an air stone for a few hours during the night. Thats what I do in my tank and seems to work pretty well.
     
  3. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Messages:
    8,952
    Location:
    Chicago, USA
    Yes, I agree with LondonDragon. Here is the problem with a pH controller: Plants don't care about pH. What they care about is having a steady supply of high concentrations of CO2. If the CO2 levels drop too far during the day they become malnourished. The pH controller has absolutely no idea about the CO2 concentration level in the tank because there are many acids in the tank that affect the pH. If you add PO4 for example this produces a little bit of Phosphoric acid. Nitrate addition or production can generate Nitric acid. There is a host of other organic acids being produced in any tank but the pH controller does not distinguish between those acids and the Carbonic acid produced by the addition of CO2. It just registers a change in pH and opens or closes a valve. The pH can rise as the plants consume CO2 or as it evaporates, but what happens if there is acid production in the tank during this time? The pH would not necessarily rise and the controller would have no idea that CO2 levels had fallen because it's not measuring CO2 levels, it can only measure acid levels. So the plants starve and the controller doesn't care. This CO2 instability can cause CO2 related algae such as hair, staghorn or even BBA to appear.

    Now, plants can't use CO2 at night. Instead they use oxygen so at night your plants are actually competing with fish for O2. Since they are not consuming CO2, the CO2 levels rise while the O2 levels fall. This can be a fatal combination for fish. Your discus could easily have died from CO2 poisoning which was exacerbated by low O2. The larger the fish the more susceptible they are to CO2 poisoning and the higher their O2 requirements are so running CO2 at night is not really optimal.

    Plants need CO2 levels to be high during the early part of the photoperiod but it's much less important in the afternoon. If you shut down the CO2 a few hours early, the plants will continue to consume the remainder of the CO2 until lights off and they will continue O2 production until lights off. The sooner you turn off the CO2 the more comfortable the fish will be overnight because of lower residual CO2 levels. That limits their vulnerability to the 1 or 2 hours that the CO2 is turned on prior to lights on.

    You don't need to throw away the controller, just limit its role to that of pH indicator only and use a solenoid on a timer to shut down the gas. It's nice to know the pH but neither the fish nor the plants are at all concerned about the pH stability, however CO2 instability does cause problems.

    Cheers,
     
  4. nrwatson

    nrwatson Member

    Messages:
    29
    That would make a lot of sense
    In relation to timers are there any that you would recommend the one that I am using with the tabs you press in seems very unreliable it has lost 2 hrs in as many weeks so syncying it with another sounds like a recipe for disaster
    Thanks
     
  5. a1Matt

    a1Matt Member

    Messages:
    2,521
    Location:
    Bromley
    I find the same with the mechanical segment style timers, they 'slip' continuously.

    I bought a twin pack of timers from Argos, based on the fact they were the cheapest I could find. No time slipping any more. Except for the fact that they trip when trying to switch on my lights I am pleased with them. For switching pumps, solenoids, etc they are great.
     
  6. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Messages:
    8,952
    Location:
    Chicago, USA
    Timers are one of the few things that I now think are worth paying extra for to get good quality. Like you I've had a case where I was getting hair algae even though my CO2 was high. I was scratching my head for weeks until one night I was woken by a telephone call. It was something like 3 AM and afterwards I went to get a cold drink from the fridge. On my way to the fridge I was appalled to see that the timer had failed and that the lights were on. The problem is that cheap electonic timers can fail just as easily as the analog tabbed ones. If you have a reputable electronic shop like RSC try to get ones from there. The electronic ones from Homebase are better than the analog ones but do fail.

    Cheers,
     
  7. milla

    milla Member

    Messages:
    241
    Location:
    Leeds
    Homebase or was it b&q not sure do a electronic timer specifically for use on lighting ballasts ( very high inital current - it is this that causes them to fail ) . They are not cheap though about £15 I think and have a 5 year warranty on them.
     
  8. nrwatson

    nrwatson Member

    Messages:
    29
    Thanks
    Seems strange that a aquarium company hasn't brought out a timer which allows for two set times
    Thanks again
    Neale
     
  9. teg1203

    teg1203 Member

    Messages:
    62
    Location:
    Mid-Wales, Powys
    On the subject of timers I am about to use a central heating timer to control lights & CO2 solenoid. The reasoning - two independent time intervals adjustable over a 7 day period with multiple time periods available throught the day. Add to this a real time clock with battery backup, so if the electricity goes the timer doesn't need to be reset or default. If you want to view the tank outside its normal lighting period just one press of a button gives an hour of lighting Depending which unit you used). I wouldn't recommend doing this unless you were safe and happy with electrical wiring. If you bought a second hand unit and a couple of sockets and wired it so you had two trailing sockets where you plugged in the lighting and solenoid it would make a neat, reliable and very flexible solution for around the £20 mark.
     
  10. a1Matt

    a1Matt Member

    Messages:
    2,521
    Location:
    Bromley
    what a fantastic idea :)
     
  11. JamesC

    JamesC Member

    Messages:
    1,276
    Location:
    Bexley, Kent
    Snap! I've used a central heating timer for years to control my lights. Looks good too.

    James
     

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