Zero Runoff Bottom Feed in Coco

Discussion in 'Coco Coir' started by PotStrainsForBackPains, Nov 8, 2022.

  1. Have been working and using a super simple bottom feed technique at times for a bit, and would like to share it. Will post some pix of recent results using it in a min.
    Note that I only use this technique some times. Mostly when running many different strains in a congested setup.

    Quick view:
    * Uses much less water, generally around 50% compared to top feed DTW
    * Seems like a slight loss of potency
    * Seems like a slight+ increase in terps, most noticeable in strains with strong terps
    * Yield loss 10-20% (veg a week longer to eliminate this)
    * Some strains will produce flowers that seem objectively cleaner than with top feed DTW

    How to
    * Must be in coco or coco+ (Royal Gold Tupur, etc)
    * Plants must be in pots that will work for bottom feed.
    * Put the potted plant in a flat bottomed container. Tupperware style containers can be perfect. Grooved bottom trays do work, but not as well.
    * Water the Tupperware, measuring how much. If the water is gone in 60 seconds, add more and raise the amount next time you water. If the water is still there in 10 minutes, use less next time.
    * First few days after transplant, you may wish to top feed while the roots go searching through the media.
    * DONT top feed to 'flush the coco' once a week or ever. If she starts to burn and you have to flush the media, flush it super heavy. There will be tons of nutrients that have migrated to the top of the coco, which will get washed in to the roots, then you get REAL burn.
    * If you put more than one plant per tupperware/tray, the ones that want more will get more, nice self regulation

    Thats it. There is no secret, thats the whole thing.

    But wait some will say! That can't possibly work! All the nutrients will just build up and eventually kill the plant due to nutrient toxicity won't it?
    Depends, but probably not, very strain dependant.
    If a strain likes to run super high EC all the way to the end, you can do the same thing with Zero Runoff Bottom Feed. Probably won't even have to lower the nutes' EC. If a strain is one that needs a strong taper to avoid burning up toward the end, then do that.
    I have only seen a few strains that required an extra amount of tapering off EC compared to when running top feed DTW.
    For the most part, use the same nutrient strength as you would in a top feed.

    More Details
    How can this work? Turns out that we create a surprisingly self-regulating system when doing this Zero Runoff Bottom Feed method.
    Post harvest media analysis showed that there is a moisture content gradient as expected, wettest at the bottom and driest at the top with a fairly smooth gradient between.
    I also found an EC gradient, and not like expected. The EC at the bottom was very close to the EC of the fertigation solution. The EC then got lower toward the middle of the container, then higher again toward the top.
    My hypothesis is that these gradients allows the plants to pick and choose to get whatever they want.
    After a few weeks, you may start to see salt crystals forming on the surface of the coco.

    Most of the yield loss is due to the plants having a sluggish week after transplanting. This can be mitigated a bit by simply transplanting deeper, but that also reduces the total volume of media that the roots with inhabit. Roots are less willing to grow upwards than with top feed, which makes sense seeing that the water is at the bottom.
    After trying a few things, seems like best way to keep yield up is to just veg an extra week.
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  2. i have bottom fed in soil with decent results too
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  3. I bottom feed all the time with coco, too lazy to deal with the runoff.. A decent "flush" every two weeks, just because. No one has ever compained the quality I get, and Im Happy with the result, so I don't Care..
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