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Water ph for soil grows

Discussion in 'Newbie Central' started by Bigby, Jul 7, 2010.


    Bigby Well-Known Member

    In the course of all of my research into marijuana growing it seemed that the suggestion for ph of water to give your plants was to have it about 6.5ph. However, recently I have found a lot of people saying that it doesn't matter what the ph of the water is as the soil will buffer it and make it right for you. This has left me confused, so I would appreciate some experienced growers opinions on the subject.


    Should water ph be about 6.5?


    Can it be anything, as the soil will adjust it to the ph of the soil?

    slomoking13 Well-Known Member

    your water ph depends on where you live and where the water is coming from. it's best to keep your water around 6.5-6.8ph for soil and then you won't have to worry about the ph drifting on you.

    Bigby Well-Known Member

    Ta for the reply. I realise that water ph varies from place to place. Mine is ph8 and I have had it suggested that I dont need to adjust this as my soil will buffer it down to the right level. I was under the impression that you had to adjust it to around 6.5ph. So what is right?

    riddleme Well-Known Member

    The reason that soil acts as a buffer is because the water is wicked out of it by the plants and as this happens the ph of the soil returns to normal (which should be close to 7 or neutral)

    the ph of rain (in most places) is 5.6 I like to ph my tap water down to 5.8 as this resembles rain as the plant wicks the water out of the soil it returns back to its original ph (as I said earlier) and as this happens different nutes become available at different times thru the wicking process see attached pic it will show what nutes are being used as the ph buffers back to normal

    Bigby Well-Known Member

    Ah ok. So am I right in thinking that if I put water in at ph8, the plant is likely to take on the excess ph (and have issues as a result) and the soil will remain at about the ph level it was at the start?
    trichlone fiend

    trichlone fiend New Member

    PH actually means "potential of hydrogen" ...your pH reading is the measure of the concentration of hydrogen ions found in whatever your measuring.
    ...since water (h2o) has hydrogen in it, and soil absorbs water....the wetter your soil is, the lower your pH will be (or acidic) due to haveing more hydrogen present.... As your soil dries, your pH will swing higher (alkline) due to there being less h20.

    ...so, you'll never dial your pH all the way in while your growing in soil. You can only try to stay "in range"...and here's how you do that.

    ...ph everything going in @ 6.5 making what "goes in" slightly acidic.
    ...add rapid release dolomite lime as a top dressing 1 tbls per gallon of soil to prevent things from becoming too acidic.
    Bigby and Dreadheadgrow like this.

    GoldenGanja13 Well-Known Member

    I always adjusted my ph after adding nutes to 6.5 every time. Being that it was a non organic grow, you want the roots to be able to take up all the nutes they can right away. Now if you where organic, then PH is not that big of deal, because the micro biotic life in the soil adjust everything for you. Nutes will kill these little workers if non organic.

    Denofearth69 Active Member

    If your tap water is at 8Ph then soil amendments can be used to address and compensate for this problem. Elemental sulphur will drop soil Ph one full point, but it will take as much as 10 days for critters in soil to convert sulphur to sulphuric acid. One potential benefit to your situation with the water is that your ferts won't easily overacidify your soil. I grow under similar circumstances as my tap water is 7.5 where I live, and with a single application of elemental sulphur, and plenty of high potency compost teas my soil Ph ranges from 6.2-6.7, well within the acceptable range. Remember that with soil things happen more slowly. Kind of frustrating when you are waiting for results, but also means that over fertilization can be caught before it is fatal and a good flushing can save your plants.
    Bigby likes this.

    Bigby Well-Known Member

    Great post - very informative. Thank you +rep :-)

    Bigby Well-Known Member

    Again, great post. Thank you - +rep :-)

    riddleme Well-Known Member

    look into Calcined Clay (what hydroton balls are made of) as it adds sulfer to your grow medium

    I use turface (brand name, way cheaper than hydrotron, 50 lbs $8 you can google it and I have a ditty on the benefits in my nuggets link

    Bigby Well-Known Member

    All good stuff guys. Not got long to go on my current and first grow, but ive learnt some lessons, both from what ive done and seen and all the posts in this thread, which I will apply to my next grow. Cheers peeps. :peace:

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