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Thread: venturi not working properly

  1. #1

    venturi not working properly

    Hey all,

    I recently changed from my external DIY reactor to the venturi reactor.

    I followed exactly the diagram in the gallery.

    my tank size is 36x18x18"

    I placed the reactor near the center rear bottom of the tank...with a spraybar spraying towards the backwall of the tank..

    the bubbles do not go around the tank as it is suppose to...the mist only makes it half way to the front and then it goes to the surface.

    i've tried spraying it towards the front of the reactor, and the opposite happens, most of the mist escapes through the back of the spraybar.

    the mist also concentrates near the center and rarely makes it to the left side nor right side of the tank

    i am feeding more CO2 in the venturi than my DIY reactor, and I am experiencing thread algae all over and my pellia are all dead.

    What am I doing wrong? Hopefully I don't need to convert to the diffuser method since I thought the venturi is just as good.

    Thanks for your help.

  2. #2

    Re: venturi not working properly

    I would place the spray vertically.
    Then place the Venturi reactor near the bottom directly in the path of the current.

    The mist coming out of the bottom of reactor should get swept away and be dispersed all over the tank.

    If not, wait till the end of the day and watch.

    Tom Barr

  3. #3

    Re: venturi not working properly

    Hey Tom,

    I've tried placing the spraybar vertically down...the problem with that is the powerhead of the venturi is in the there is less current since most of the current is being blocked by the powerhead.

  4. #4

    Re: venturi not working properly

    i have same setup in one of my tanks. set your reactor just behind spraybar as close to bottom as possible.outlet water will pull small bubbles from reactor.also it helps to have inlet at opposite end of tank to help pull water flow.set a powerhead at same end of reactor position just below suface to get motion and help distribute bubbles.regards,cornhusker

  5. #5

    Re: venturi not working properly

    This is the result after a week:

    CO2 is still low. I don't get BBA anymore but I'm getting quite a lot of thread algae and GSA on the glass (even with high PO4)

    My CO2 bubble rate is about 2.5-3 bubbles/sec (I just eye it)
    And this amount is already alot for a 50G tank...I don't want to increase it any further because I am refilling my 10lb CO2 tank like every 3months already.

    I know my bubble rate is enough, and my venturi is made the same way as the one in the gallery.

    So what is the problem?

    I have a spraybar that is spraying vertically down, even though 1/4 of the current is blocked out by the powerhead of the venturi. The venturi is located as far down as possible, almost touching the substrate.

    When I first had this setup, I did not have my second spraybar setup for surface movement. My fishes were surfacing really badly. But after I setup the surface movement, the fishes no longer surface anymore (they don't even gasp that hard either) and I did not change the bubble rate for the CO2.

    So does that mean I have too much surface movement? will that cause a problem?


  6. #6

    Re: venturi not working properly

    No, the Surface movement is fine now.
    What you need to do is have the CO2 mist coming out the bottom shoot around the tank in a better pattern.

    You simply need to try and play around till you see the bubbles making it to most of the tank's location.

    There is no simple hard and fast description of this, just adjust and watch where they go. It's okay if the bubbles do not go "everywhere" but most places(60-100%)

    Variations in the planting, scaping, tank sizing etc makes it hard to account for it. But your CO2 is up, but not all the way yet.

    1-2 bubbles a second typically will di it for such a tank.
    Solenoid for less loss and reduced tank refills will also help.

    Tom Barr

  7. #7

    Re: venturi not working properly

    Tom, gasping is fine if its not at the surface since you mention his CO2 is not all the way yet?

    Peter Gwee

  8. #8

    Re: venturi not working properly

    No, they should never gasp.

    I have tested the surface movement thing 4 times lately and each time they came up with no change in either the CO2 bubble rate nor the pH.

    So the entire night time aeration thing: BS.

    But I already knew that but after seeing it to make sure a few times, now is war:-)

    I'm on a bit of warpath lately anyhow on the ADA product line, I like the soil, tanks(not the little ones, can do much much better $$ wise), some glassware.
    Most of the rest is chaff.

    Best results to date:

    CO2 mist
    ADA amazonia soil(no powersand) + mulm.

    I have several tanks to compare the full ADA line against as well as an entire LFS that uses and carries nothing but ADA.

    I am both helping ADA and ripping on them at the same time.
    Same case for Dupla way back when and most things and PMDD etc.

    I do not blindly accept things.
    Nor should you.

    But at least try them to see if they work for the reason's claimed.
    Amano still thinks excess nutrients in the water column cause algae.

    Tom Barr

  9. #9

    Re: venturi not working properly

    I've seen what the mist can do but I've had real problems dispersing the mist all over the tank (a Fluval "Lily-pipe" in back-right corner and a venturi loopback reactor beneath it) because of the thick vegetation. The plants near the reactor on the right went nuts, but the left part was a problem.

    Because the Fluval is old and can't deliver enough current with a spraybar and tight rigid fittings which were hard to move, I adjusted the aquascape instead of the equipment

    Now I have a triangular layout with the highest point on the left and an open area and the "lily-pipe" on the right managing to mist everything real good.

    The cool thing about the mist is that folks see the need of good circulation. I bet that with the same setup that disperses the mist evenly throughout the tank you would get great results without the mist also.

  10. #10

    Re: venturi not working properly

    who has a venturi and uses a spraybar?
    I need some examples as to where to place them.

    I currently the venturi at the back center, near the substrate

    I have a spraybar that is above the venturi and is spraying vertically down against the venturi

    there is actually quite a lot of micro bubbles floating around the tank, but I do not know if that is caused by the surface movement.

    can too much light be the cause as well?
    I have 2x96W over the 50G.
    but I have one 96W on for 11 hours. and the other one on for 8hours.

    I've tried to use only one light. but because my tank is 18" wide. and have quite alot of plants. there isn't enough light in some places and plants will die very quickly (also there is no pearl)

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