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Seaweed extract and humic acid

Discussion in 'Fertiliser - mineral supplements. Aquaponics syste' started by stevegoldy, Sep 6, 2016.

  1. stevegoldy

    stevegoldy New Member

    Jun 13, 2016
    South Australia
    I am no professional by any means, so please correct me if I'm wrong
    I have read on some threads that peopls add things like seaweed extract (and I do to) to "fertilise "there plant, even while dealing with nutrient toxicity
    This is some what incorrect, while it dose have some micronutrients it is more of a root tonic as It stimulates root growth

    Some others panic when the water turns dark when they add these extracts. I think this is a good thing, especially if you have an algae problem, because you are artificially darkening the water, which algae will not thrive. However you could argue that the higher nutrient level would increase algae growth. And I agree

    So now my question is why not use humic acid which is a soil conditioner
    And this is my understanding
    Essentially it increases the cat-iron exchange which is the increased ability of the media to hold nutrients readly available to the plant, or it use the nutrient that already there and puts it directly where that plants want it, also it darkens the water(a tablespoon in a 20ltr bucket turns the water black!)thus using the available nutrients and artificially darkening the water to reduce algae growth without adding nutrient
    Oh and here's the best bit, worms love it, it is found in composts that are rich in carbon, compressed dried leaves are one of the best sources
    FYI Murray would be putting it his system when he does compost tea in the Indy23

    as I said at the beginning "I am no professional by any means, so please correct me if I'm wrong" I value feedback
  2. Yabbies4me

    Yabbies4me Administrator Staff Member

    Jul 27, 2010
    What nutrient toxicity are you referring to Steve?

    People are adding Seaweed extract primarily for the trace elements it contains, ie: Iron, Magnesium, Zinc etc, plus the Potassium it also provides, which is a somewhat common deficiency in aquaponics, usually as a result of over planting, especially of flowering/fruiting plants. They are adding it because their system may be generally low in these nutrients, not because of a nutrient availability issue, which humic acid may well help with… but it will not add them to the system.

    The seaweed extract is usually added in very small, regular doses, ie: around 2x capfuls per 1000L every two weeks, or every week if a system is heavily planted with flowering/fruiting plants and/or large leafy greens. This is definitely not enough to colour the water black, or even dark brown. I would suggest that if you are adding Seasol and your water is turning noticeably brown, then you are adding way more than what is required and could well be contributing to a nutrient imbalance in the system.

    I have my own brand of Humic acid product that I have sold for 14 years, and I would love to say that it's a must have for aquaponics, but I have trialled it in my systems and can’t say that I have noticed much, if any difference. That's probably due to the natural bacteria, fungi, enzymes, worms etc that exist in aquaponics... Hydroponics on the other hand, it works really well in, there is definitely a noticeable difference in plant health, grow rates, yields etc.


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