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CO2 Misting for 30 gallon

Discussion in 'CO2 Enrichment' started by Henry Hatch, Apr 27, 2009.

  1. Henry Hatch

    Henry Hatch Guru Class Expert

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    I've been playing around with misting again. I tried a modified impeller on a power head in my 30 gallon to create a needle wheel. The mist I got was not that fine so I stuck the co2 line into a piece of dense foam to make small bubbles and that was a big improvement.

    I would like to try and make the mist even finer so I was thinking about buying a needle wheel pump. The pumps I looked at on line had pretty high flow rates for my tank. I was thinking I could attach a spray bar to create less turbulence and help get better co2 distribution.

    I'm looking for suggestions on a pump that could be used on my 30 gallon.

    Henry
     
  2. Gerryd

    Gerryd Plant Guru Team
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    Henry,

    A pump just for c02 I assume?

    How about one of the in-line venturis from Kent?

    I know Tom has mentioned decent success with them and your tank is not that large and may work well.

    I think they can be run inline on the filter outlet.

    Perhaps a small needle wheel and venturi combo?

    Hope this helps.
     
  3. mi5haha

    mi5haha Prolific Poster

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    There is a 10W needle wheel pump manufactured. Not sure whether it is available in your market there.

    To slow the flow down, you may use a 20mm dia PVC pipe, cut into a 10cm or 12cm piece in length, and drill small holes (around 2mm in dia. for each) full over one side (180 degrees) from top to bottom. Leave the other 180 degree undrilled.

    Block one end, and connect another end (you may need to use adapter since the diameters are different) to the water outlet of the pump. Make this PVC pipe in vertical position, and turn the side with the holes to face the area you want to spread Co2. This is like "broadcast" by a microwave antenna.

    The rule is that try to use thicker (than the pump water outlet, so the water pressure will reduced) pipe, and water flow coming out from the pump will firstly run to small holes at the top of the PVC pipe, and then slower motion water flow to the holes in lower position. The pipe itself can regulate the flow itself by these small holes. So the water flow will be much more gentle in this way.
     
  4. ibnozn

    ibnozn Subscriber

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    Hagen Elite Mini filter? There's a thread over on APC in the DIY forum raving about it.

    With what you have now, instead of the foam could you try a limewood airstone? Limewood produces microfine bubbles to begin with so running this mist into your powerhead intake should work pretty well.
     
  5. Henry Hatch

    Henry Hatch Guru Class Expert

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    I did try limewood. However, with diy co2 I did not have enough pressure to maintain a decent flow of bubbles.
     
  6. Henry Hatch

    Henry Hatch Guru Class Expert

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    I made another home brew needle wheel and using the dense foam it appeared to work quite well. I got a very fine mist. My co2 levels actually went up which seems counter intuitive. I would expect my drop checker to show lower co2 based on my assumption that there would be less dissolved co2 in the tank and co2 misting should be more lossy with bubbles rather than fully dissolved co2 in a typical co2 reactor. Perhaps I'm getting better co2 distribution.

    I'm going to the LFS to pick up a few things to make Tom's venturi reactor. It will be interesitng to compare the two.
     
  7. shoggoth43

    shoggoth43 Lifetime Charter Member
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    You may also be seeing much better CO2 if the bubbles are finer and dissolving better as they'll "float" around the tank much longer and may never make it to the surface.

    -
    S
     
  8. Henry Hatch

    Henry Hatch Guru Class Expert

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    I wanted to give an update on my co2 misting adventure. My 30 gallon tank is now loaded with fine mist. I've have had it running for about a week. My plants are responding extremely well. Java moss and fine leaved stem plants are covered with co2 bubbles. It certainly appears that there has been a significant affect on growth and general vitality. I have 60 watts of t8 lighting with a max PAR reading of about 70 at the substrate.

    I originally tried modifying an aqua clear power head impeller by melting holes with a hot needle. I was not that happy with the results. I then took the impeller of a maxi jet 600 and modified that and it worked much better. When I looked at the impeller of the maxijet and compared it to a comparably sized aqua clear I noticed that although the aqua clear impeller had six blades instead of the 5 blades on the maxi jet, the blades on the maxi jet were longer. The impeller design may have made the difference.

    From my reading it appears that the main reason misting works is that plants can much more efficiently absorb co2 from the bubbles which attach to the plants and that the area around the co2 bubble has high levels of co2 which help absorbtion even if they do not directly attach to the plant.

    Additionally I read that co2 misting works in part because of better circulation.

    Even though misting is less efficient at dissolving gas I think the increased efficiency of absorbtion more than make up for the loss of gas due to bubbles going to the surface.

    One other thing I noted which may be unrelated. My tank is gin clear. It looks like it does after I run a diatom filter.

    I'm not sure how much I will like the look of a tank that looks like a bottle of champagne over the long hual. However, this exercise has reinforced and made me more determined to good co2 into my tank however I have to do it.
     
  9. Tom Barr

    Tom Barr Founder
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    Well, the CO2 mist gives a good non limiting method to make certain about the CO2, then after things are running well for a few weeks, you can start testing other thing, reducing the light, or playing with reduced or excess levels of ferts one at a time etc.

    Did you use the mesh modification to the maxi jet?
    You can still use a spray bar type of attachment and place the powerhead and mist bar on the bottom back and have the mist go from the bottom rear to the front bottom and the bubbles rise up through the Leaves as it travels, this yields less annoying bubbles, more pearling and really good diffusion.

    I'm about done now with using the disc, I ended up with BBA in the tanks where I left the bubble rates the same vs the Mazzi methods. I increased the flow of the mist coming from the disc and then added about 30-40% more CO2, now no issues and good growth.

    Next is the Maxi jet modifications using the mesh impellers and a hang on the back type of thing. I'll do a spray bar for 3 of the tanks, one tank will remain using the disc as a reference and it's been doing very well anyway.

    Regards,
    Tom Barr
     
  10. Henry Hatch

    Henry Hatch Guru Class Expert

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    I did not do a mesh mod to the maxi jet. I just heated up a needle and made holes in a checker pattern. How would I do a mesh mod ?
     
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