Why is required pH for hydro and soil different

Discussion in 'Growing Marijuana Indoors' started by FunSizeKaZKaZ, Dec 31, 2017.

  1. I've seen soil pH recommendations being 6.5-7.0 and hydro 5.5-6.5. Why is that?


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  2. Read up on "Cation Exchange Capacity", that should help you understand why pH levels are different for hydro and soil....
     
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  3. The feeding process is different with each method. In hydro you are feeding the plant elements that are ready to use. They are in a form that needs little to no processing by the plant to utilize.

    In an organic/soil fed plant growth process the elements fed to a plant are not in a readily usable form. They must be broken down by soil microbes that then feed them to the plant via the mycos system.

    Feeding with hydro is like feeding a person vitamins and minerals directly to the bloodstream with a feeding tube. Feeding with organic amendments/composts is like a person eating a sandwich that must be broken down by the digestive system before it's used. That's why organics have a low potential to burn the plant. Plants are burned by too high of concentrations of readily usable nutrients, not ones that are organically locked in compounds.

    The optimal ph for direct absorption of nutrients is not the same range as the ph range that promotes the optimal health of organic breakdown and feeding of those nutrients by microbes. That's why they are different.
     
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  4. The ph charts I've seen and go by for cannabis have a hydro range of about 5.8-6.2. Anything outside of that is going to cause slowed uptake of certain elements.
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    As you can see by 5.8 magnesium is dropping off significantly. Over 6.2 and you lose phosphorus. You can't get by with reduced uptake of either of those.

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    Below 6.2 in soil is going to block out calcium.
     
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  5. Damn you're the man Tbone you've got all the answers for me. Thanks again your teaching me


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  6. Oxygen availability to roots. Oxygen is more abundant in hydro so ph is lower.
     
  7. #10 Tbone Shuffle, Jan 1, 2018
    Last edited: Jan 1, 2018
    I wouldn't say this is true at all. A well constructed soil medium with plenty of perlite/vermiculite would have the same amount of oxygen to the roots as a coco or promix grown hydro plant. They would still grow off of those different ph charts to have optimal health.

    There's many different hydro methods. It's actually endless. Many of them vary little from soil growing except the feed and ph. Promix is very similar to soil grows in how it behaves. It is both used by hydro growers as a medium and soil growers as a base to mix in composts, ect. If you're feeding it with hydro bottles target 6.0ph. If you use the same promix to amend and grow organically you're going to target 6.5ph.

    The only instance where you may have an oxygen advantage is in DWC but thats marginal. You get a lot of air through promix/30%perlite when it's damp. The roots are mostly in water. The only air they get is bubbles.
     
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  8. I know this isn't on a correct thread but if your willing to answer me one more question that's been weighing on me. I feed my plants bat guano and earthworm castings. Every two other feedings I usually add a little molasses. I am wondering if you know why molasses is suggested all over. Does it feed microbes in the soil or does it give the plant some kind of sugar that helps in the flowering stage? Imma post a pic of my Gorilla Glue plant also just cause lol grown under 1 viparspectra 300w and 1 Mars hydro 300w


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  9. The pic is of one of the lower branches that has stretched to the top of the canopy. My main colas are much larger. But I like this pic. I accidently double posted my bad...
     
  10. #13 Tbone Shuffle, Jan 1, 2018
    Last edited: Jan 1, 2018
    The molasses does both but it is mostly microbe food. It's very beneficial to plants and its used commercially on large scale crops.

    I was part of a long molasses thread a while back and ended up looking up some side by side trails done by universities. Simply adding molasses to their routines resulted in a 75% increase in the largest and highest quality onions. There was other similar results with other crops.
     
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