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Updated Beginners Guide to PH in Marijuana

Discussion in 'Absolute Beginners' started by GigZ-16, Mar 22, 2008.

  1. Beginners pH Guide.

    I posted this yesterday, but I decided to add a few more helpful things and repost it. Sorry for the double posting.

    What is pH?

    pH is the measure of how basic or acidic a solution is. The pH of a substance is measured in a numerical fashion using a scale of 1 through 14. A solution with a pH higher than 7.0 is considered to be basic and is called a base (or alkaline). A solution with a pH less than 7.0 is considered to be acidic and is called an acid. The strength of an acid or base can be either weak or strong. The stronger an acid or base, the closer the solution is to its respective number on the pH scale (basic being 15 and acid being 1). The weaker a solution or base, the closer its pH value is to a neutral rating (neutral being 7). Every full point change in pH signifies a 10 fold increase or decrease in acidity or alkalinity. For example, water with a pH of 6.0 is 10 times more acidic than water with a pH of 7.0, while water with a pH of 5.0 is 100 times more acidic than water with a pH of 7.0.

    Here are some examples of acids and bases and their respective pH ratings.
    -.2 Battery Acid
    1.2 Gastric fluid
    2.2 Lemon juice
    3.6 Orange juice
    4.4 Beer
    5.6 Pure Rain
    6.6 Milk
    7.0 Distilled water (H[SUB]2[/SUB]O)
    8.0 Seawater
    9.2 Baking soda (NaHCO[SUB]3[/SUB])
    10.6 Milk of Magnesia (Mg(OH)[SUB]2[/SUB])
    11.4 Household ammonia (NH[SUB]3[/SUB])
    12.8 Household bleach (NaClO)
    13.6 Household lye (NaOH)

    What is PH? pt. 2

    pH is defined in chemistry in several ways. An acid is sometimes defined as a solution with the potential to donate a Hydrogen ion (H<sup>+</sup>, also called a proton), or to accept a Hydroxide Ion (OH<sup>-</sup>) from a base. A base on the other hand is sometimes defined as a solution with ability to donate a Hydroxide Ion, or... you've guessed it, accept a Hydrogen ion. Low pH corresponds to a high hydrogen ion concentration and vice versa, while a high pH corresponds to a high Hydroxide ion concentration and vice versa.

    Why is pH important when growing a plant?

    Any substance that is going to be used to support any form of life has to fall within a certain range on the pH scale. The range may vary from organism to organism. Marijuana is no different. The soil, nutrient solutions and water all need to be monitored and adjusted to stay within a specific range, depending on your method of growing. When growing Marijuana in soil, the soil and water supply should stay within the range of 6.5 to 7.0, while in hydroponics the nutrient solution should stay within the range of 5.5 and 6.0.
    When a plant's soil or nutrient solution becomes too basic the nutrients become unavailable to be absorbed by the roots. When the soil or nutrient solution becomes too acidic the acid salts will chemically bind together the available nutrients and they will be nonabsorbent by the roots. When this happens the plant will show tell-tale signs of stress. Some novice growers and even a few seasoned growers will falsely think they need to add more nutes or fert, which only compounds the problem by usually causing toxic salt build-up. Toxic salt build-up stops the roots from absorbing water. So remember as a rule of thumb to always test the pH before reducing or increasing a fert or nute dosage!
    The pH of your soil or hydroponics setup can be measured with a simple 20$ or 30$ pH Tester, or small one time paper tests. These are highly recommended when growing any plant.

    Some things to remember when using an electronic pH tester

    1. Clean the probes of the meter after each test and wipe away any corrosion.
    2. Pack the soil tightly around the probes.
    3. Water soil with distilled or neutral pH water (7.0) before testing.
    4. The meters measure the electrical current between two probes and are
    designed to work in moist soil. If the soil is dry, the probes do not give
    an accurate reading

    What causes fluctuations in pH?

    When growing in soil any fertilizer you use can cause an excess build up of salts when it decomposes in the soil. This almost always results in a more acidic soil which stunts the plant's growth and causes brown foliage. When using a Hydroponics set-up the nutrient solution can very easily cause a fluctuation in the growing reservoir. Other common reasons as to why soil may become too acidic when doing outdoor grows are rainfall, leaching, organic matter decay and a previous harvest of a high yeild crop in the same soil. In dry climates, such as the desert Southwest US, Spain, Australia, etc., irrigation water is often alkaline with a pH above 7. The water in rainy climates, such as the Pacific Northwest of North America, the UK, Netherlands and Northern Europe, is often acidic with a pH below 6. Lightly sandy soils with little clay and organic matter are quicker too become more acidic. Another common mistake is that a grower will mix his soil unevenly, leading to "hot spots" in the growing medium, so mix all ratios as well as you can.

    How do I raise/lower my pH?

    A great way to regulate the pH of your soil is to use Dolomite Lime(calcium-magnesium carbonate). While growing Cannabis plants in containers, mix one cup of fine dolomite lime for each cubic foot of soil, then lightly water it. After watering, mix it once more and wait a day or two before checking the pH. While growing in an outdoor garden, follow the dolomite lime manufacturers instructions. Dolomite Lime works well because it has a neutral pH rating of 7.0 and tends to keep the soil a constant pH throughout the entire life cycle of the plant. This is a highly recommended method of regulating your soil pH.
    If you find the pH of your soil or Hydroponic reservoir to be too acidic or basic you could add either pH up or pH down. These are chemicals sold at places like Home Depot or any Gardening store. They usually come in one liter bottles and are to be diluted in the water used to water the soil growing plants or the Hydroponic reservoir according to directions on the packaging.

    Some examples of Home remedies to raise/lower pH are as follows:
    1.Lemon juice. 1/4 tbsp can bring a gallon of tap-water from 7.4 to 6.3.
    2.Phosphoric acid. lowers pH and provides Phosphor too!
    3.Nitric acid. lowers pH.
    4.Hydrochloric acid. strongest way to lower pH
    5.Hydrated lime. flush soil with a teaspoon per gallon of water to raise pH.
    6.Baking Soda. eats acids to raise pH.
    7.Calcium carbonate. raises pH (very strong)
    8.Potassium silicate. raises pH.

    What are signs of a PH fluctuation in my Cannabis plant?

    A Cannabis plant can show signs of a pH flux in several ways. The leaves may begin to turn yellow or brown, dry up and/or shrivel on the sides into a straw like shape. Keep in mind however that other deficiencies and disorders may show the same signs of damage, so don't jump to conclusions until you do some testing and adjusting to your plants and their growing medium.

    Some things to remember(I didn't write these ones)

    1.Always test the pH of raw water and drainage water with a pH meter.
    2.Raw water pH above 6.0 helps keep fertilizer mixes from becoming too acidic.
    3.The pH level is much more important in organic soil gardens than in chemical
    hydroponic gardens. The pH dictates the environment of bacteria necessary to the
    uptake of organic nutrients.

    I hope I helped at least one or two people.
  2. wowwww thanks, i think im going to water with 1/2 rain water with lime, ph level 6.8, and 1/2 reverse osmosis filtered water, 7.0 and alternate the feedings from one watering method to the other, every other time.
  3. all your freakin guides should be stickied bro:hello:
  4. Pretty good thread however I like a hydro pH of 5.2-5.8 and soil from 6.2-6.8. Gives more of a buffer and a wider range when plants are flourishing out of our “must adhere by" numbers ;)
    Oh and don't use lemon juice in hydro only soil; it can kill hydro plants.
  5. We all have our preferences when it comes to things like pH and such. Thanks for the info on lemon juice, I'll add it to the guide.
  6. lol, thank you, I put alot of effort into them.

  7. Good post thanks. Have 5-8 (5 white widows, 1 Ultimate Idica, 2 yet unknown) outdoors this year. Should come in very handy.
  8. my ph is about 8 how im gonna make it 7 or 6.5 thank u

  9. read what he said you obviously dident cause it explains how to lower the pH level.
  10. :hello:ph never a problem again,
    and i did the lime on the water and
    the ph 7.5to8.0 was down to 5.0to5.5
    never this good, thanks dude:cool:
    i had this light bulb call filiphis MH from homedepot,
    and i had for 3 weeks about 15 inch from the plant,
    and they grow only 5 inch, after i put a HPS 55.oool
    my plants are giant and very fat in to the 5 week no
    sign of buds, strain is autoflower lowryder2 feminized,
    look good now but i think i lost the maxim yield
  11. #11 cantharis, Mar 29, 2009
    Last edited by a moderator: Mar 29, 2009

    Well , as you have not done this correctly, let me define pH for you:

    pH is the negative of the exponent of the concentration of hydrogen ions in aqueous solution in term of grams per litre.

    ie, a neutral solution contains 10E-7 grams per litre of hydrogen ions, and has a pH of 7.

    a slightly acidic solution may contain 10 times as many hydrogen ions as a neutral solution, a concentration of 10E-6 grams per litre of hydrogen ions, and will therefore have a pH of 6.

    a slightly alkali solution may contain 10 times fewer hydrogen ions compared to a neutral solution, a concentration of 10E-8 grams per litre of hydrogen ions, and will therefore have a pH of 8.

    Oh, and I have never, ever measured my pH. It is simply not that important, MJ can flourish over a wide range of pH values, as can many plants. I averaged 18 ounces (dried) a plant last grow, but people who can´t get 2 ounces still warn me about nute lockout (whatever that is).
  12. I used a ph meter for my first grow... never needed it after that...
  13. #13 L.L.Rain, Mar 29, 2009
    Last edited by a moderator: Mar 29, 2009

    actually, although very helpful in alot of ways, it really wasnt all that clear imo about how to lower the ph in soil...
    the ph of my outdoor soil is also 8.0, siktir git, haha just realized this is from last year, lol, anyways i'm adjusting the ph by mixing in pure peatmoss (slightly acidic) and using this stuff (if i can get the pic to post). there ya go, organic ph buffers. man iwish the pic came out bigger, it says garden sulfur on it, was $7.55.

    Attached Files:

  14. Okay say you already have plant that are flowering and need to lower soil ph what is the simplest way to do this. My plants had a late start and arent going to produce alot but they are from some that i was lucky to get two seed from. Anyway they are flowering but i noticed the smallest one the large fan leaves have started to turn yellow. None of the other leaves are and from what i can gATHER my ph is high. I havnt gotten a way to test it but am going to asap just need to know how to lower it if it does end up being elevated.
  15. Do I have to lower the pH level of my tap water when I gewrminate the seeds? or is my regular tap water (7-8 pH) level water be ok for germinating, and then ssoak my rockwool cubes in a pH down and water solution? If I missed this answer already I do apologize, any help is appreciated thanks!!!
  16. ive been having problems with my PH....this grow(my second grow) im growing 10 hawaiian snows and 19 SLH...i acidentally pulled the head off one trying to get the shell off lol. but one of my improvments for this grow was to use ph ajusted sink water....i let it sit for 4 days to evaporate the chlorine but it still reeks of chlorine.i tested the water and it has a ph of 8 or higher. so i ajusted to 5.5 to 6 with PH down from the grow store. i give my plants this shit and its still fucking them up. so now im forced to use bottled water again witch starts to get expensive. they are about 2 weeks old and the leaves just started getting twisted and white spots on them. last grow it was the bugs and now its ph.

    id put up photos but my phone dissappears from the computer 2 seconds from pluging it into the usb port
  17. Thanks for the guide, it is very informative.

    Ok, here is how I raised and lowered my pH levels. I use 1 liter bottles to feed my girls, so I have added a teaspoon or less of baking soda to raise it and vinegar to lower it. Just use small amounts at first, hope that helps.
  18. I just tested my soil using a $20 digital moniter that you just stick into the soil. It said the pH was 5.8 so should I add a bit of baking soda?about how much?
  19. #19 Rippedmofuck, Aug 9, 2011
    Last edited by a moderator: Aug 10, 2011

    Hey, just looked at this guide added less than 1/4 tsp of baking soda to my nute mix and now im worried about the SODIUM (SALT)!!! WTF is gonna happen this watering? First time i've tried this also definately getting some hydrated lime next watering just wondering what should i expect?
  20. #20 Rippedmofuck, Aug 9, 2011
    Last edited by a moderator: Aug 10, 2011

    As a ph up buffer.

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