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Grow bed depth

Discussion in 'Equipment' started by TheNative, Apr 16, 2010.

  1. RupertofOZ

    RupertofOZ New Member

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    And Matt, Yabbies and yourself are proof indeed that shallow growbeds can/will work...

    And nobody has ever said differently....

    Most of the argument in favour of shallower grow beds, or conversly against deeper grow beds... is about questions of appropriate, and comparable filtration capacities vs footprint....

    The point I'm making is that with appropriate grow bed filtration capacity, worms, and stocking densities.... auxillary bio-filtration isn't necessary....
     
  2. SmokinJ

    SmokinJ New Member

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    Clarification of my original question

    I understand the importance of 300mm depth and agree. My question was in regards to the actual depth of the media. Looking at the systems on the aquaponics site, the tanks are 300mm but it looks like the media only comes up to 250-275mm. If the media was in fact 300mm then it would be flush with the top of the growbed tank. I apologize for the lack of clarity in my question. The reason I ask is I don't have access to marine grade tanks in the U.S. and I am looking at other options in which I am not comfortable with the weight of gravel. I was trying to calculate what it would cost me to purchase clay beads and so I needed to know how much I would need. I also thought about using creek gravel on the bottom and clay on top to help lighten the load.
     
  3. RupertofOZ

    RupertofOZ New Member

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    A grow bed measuring 2m x 1m x 320mm... ie a standard 500L grow bed... requires 10 x 50L bags to fill it to within about 50mm from the top...
     

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  4. Murray

    Murray Site Admin Staff Member

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    That is not a bad option, it is frequently done by members with good success.

    It is important to understand that the 300mm (1') deep bed is not a rigid requirement that if not strictly met will spell doom. It is just a standard that has proven to be ideal. Yes it is true that most beds end up with 270 or 280mm of media depth and everything works just fine.

    Weight is a serious consideration. Make sure your under supports are good and robust. if the container is a "hardware store" type of poly trough or tray it may also need side support to stop the sides bulging or even splitting from the weight of the media.
     
  5. Wesley

    Wesley New Member

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    Bacteria and media

    I am in the process of building some beds. I am a newbie at all of this so far as the "actually doing it" is concerned, but have read and soaked up all I can on this and other sites. A huge thank you to all who contribute by the way!

    My question is this. I understand that the bacteria needed for the transformation of ammonia live on the media. What I don't understand is the relationship that they share with it in regards to the moisture surrounding it. In other words, is the media that they reside on part of that which is in the flood and drain zone, or do they live in the media that is in the very bottom of the bed as well (that part that never really drains fully).

    While working on the bell siphon, I am able to get most of the water out, but not within the last 2 inches. Is it important to drain this as well, or am I missing something? Thanks!
     
  6. Murray

    Murray Site Admin Staff Member

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    The beneficial bacteria live all through the system but principally on the grow bed media surfaces. It is true that the last 50mm (2') may not fully drain....doesn't matter one little bit. That last bit of water is exchanged each time the bed floods and drains.
    They ( the bacteria) do need water and oxygen to flourish, so when the bed drains air is forced by atmospheric pressure down through the media delivering fresh air (oxygen) to the roots of the plants and to the beneficial bacteria and the myriads of other bacteria, protozoa, fungi and so on that make AP what it is, a wonderful ECO system. The water also delivers oxygen and of course nutrients.
     
  7. tpilk

    tpilk Super Moderator

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    SmokinJ,

    Another factor I would consider is what plants you'd like to grow. Not only is river rock much cheaper, but it will hold tall and or heavy plants more securely - tomatoes are one example. Clay balls are certainly popular and sure, people grow tomatoes in them, but I have read a number of posts from folks converting back to either a base, or the entire GB filled with rock simply for holding power. Bacteria will be happy either way.

    I haven't actually done the math, but I'm guessing the savings on buying (or screening your own free) river rock, over the cost of hydroton would build a nice, stout support for your GB's.
     
  8. Jamie Greer

    Jamie Greer New Member

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    We are wanting to recycle water from our Fiber Mill used in processing fleeces of sheep. We use a large volume of water and was wondering if grow bed that 5'x5'x3 1/2' is to large. Would a bell siphon work for this or should we look at doing something else to recycle the water we use? Thank you.
     
  9. Bryce duke

    Bryce duke New Member

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    Hi Jamie,

    What volume of water are you talking about? and also are there any contaminants in the water after use? i.e Lanolin?
     
  10. Jamie Greer

    Jamie Greer New Member

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    We would be using up to 600+ gallons of water per day. There would be lanolin in the water but the soap that we use is an organic soap. The water would just be recycled back to our storage tank and then reused. There is only 1/4 cup of soap used for like every 30 gallons of water.
     

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