Effective water circulation?

Discussion in 'Carbon Dioxide (CO2)' started by Londinium, 29 Jan 2009.

  1. Londinium

    Londinium Newly Registered

    Messages:
    17
    Location:
    London
    Hiya,

    I'm very new to this hobby and have a very small, rather odd shaped tank (24"x8"x8"). I call it my learning tank cos I've learnt it all the hard way (must admit have enjoyed every last minute of it...partner thinks I'm obsessed!).

    Anyway my main problem has been effective CO2 distribution...basically I dont think its happening that well and I'm not sure if I have too much or too little water circulation or even how to tell what is too much and what isn't.

    I have an Eden 501 external filter and lily pipes. I've tried the output pipe at two different angles - one diagonal which seems to improve water circulation around the tank (ie the water surface moves in all areas of the tank but I wonder if it will mean increased loss of CO2 (my HC seems to stop pearling witht this arrangement). I've also tried the outflow not angled. The water movement around the tank appears lower as the surface furthest from the outflow doesn't move but my HC pearls....

    How much surface movement do I need?

    As my tanks is so shallow I was thinking of placing my diffuser under the inlet lily pipe so the bubbles would go through the filter and have more chance to dissolve...do you think this a good idea..

    Many Thanks, Sam
     
  2. Themuleous

    Themuleous Member

    Messages:
    4,126
    Location:
    Aston, Oxfordshire
    Hi Sam, Sam here :)

    I have two tanks of this size and it was also my first tank when I stated with plants. I really like the short but long dimensions, I think it gives a better illusion of size than more boxy shaped tanks.

    Anyway, I have been using the Eheim classic 2211, which is also rated at 300lph so I think you can easily achieve the required flow rate. The issue might be the glassware unfortunately. Clive (Ceg) always raves about the issues with glassware (correct me if I'm wrong Clive or anyone else) and certainly on such a low tank glassware my not create the correct flow patters. That said you might not have an issue with flow at all, it could be something else.

    What makes you say you've got poor flow? Don't necessarily relate a lack of surface movement to a lack of flow.

    I think you may have answered your own questions ---> listen to the plants. If you get the HC to pearl with one configuration and not the other then thats your answer!

    You also dont want lots of surface water movement as it drives off CO2 which is a waste.

    The idea of having the CO2 go directly into the filter is a good one, this often achieves max diffusion. Just watch that you dont get pockets of CO2 build up into the filter.

    Here's my journal of my 24x8x8 tank in case you're interest :)

    viewtopic.php?f=35&t=635

    Sam
     
  3. Londinium

    Londinium Newly Registered

    Messages:
    17
    Location:
    London
    Hi Sam,

    Yeah I was kinda wondering if the glassware might be a problem with such a shallow tank...bit gutted cos i think they look so nice!

    The reason I'm not so sure about the circulation is that when I have the outflow directed along the short side of the tank there is no surface movement on the other side of the tank and I was thinking this might be an issue...does the surface need to move over the whole tank? I was worried I may get a surface film or something if it didn't move.

    Just outta interest do you think it may be better to have a spray bar instead of the outflow lily pipe for this shaped tank?

    Am gonna try the diffuser under the inlet tonight and see if I can get more CO2 diffused into the water...hopefully my filter wont blow up! :)
     
  4. YzemaN

    YzemaN Member

    Messages:
    183
    Location:
    Copenhagen
    I believe the Eden 501 has a small "venturi" tube attached to the impeller housing meant to suck out any build-up of air.
    Look here:
    Eden 501 Instructions
    Bottom left on the second page. Part T
     
  5. Themuleous

    Themuleous Member

    Messages:
    4,126
    Location:
    Aston, Oxfordshire
    Right, well that helps sort that problem :)

    The only reason I like to have some surface water movement is to stop the oily film developing, but you could conceivably run the tank with NO surface water movement and it'd not be a problem, providing there is sufficient under the water. The plants will provide enough oxygen for the fish and inverts.

    A spray bar would prob give you better flow to be honest, but I know what you mean about the glassware, it does look pretty cool :)

    Sam
     
  6. Londinium

    Londinium Newly Registered

    Messages:
    17
    Location:
    London
    Well I placed my diffuser under the inlet of the lily pipe...appears to be working great! Would definately recommend this is anyone has a shallow tank! Have even been able to turn down the CO2! Have plenty of movement under the water and now not worried about the surface moving so much.....oooh I love this forum!

    ps and my filter is still in one piece! :)
     
  7. Themuleous

    Themuleous Member

    Messages:
    4,126
    Location:
    Aston, Oxfordshire
    Cool glad you got it sorted :)

    Sam
     

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