Ph of runoff in soil grow

Discussion in 'Organics' started by MDEVA, Jul 10, 2012.


    DrGreener New Member

    hey bud IMO water less more frequently

    Bigby Well-Known Member

    I too have been researching similar issues to those raised in this thread. One thing I discovered is that when using organic nutrients (certainly the biobiz range) there are NO salts present, meaning there are none to build up. Thought I'd share as it feels relevant to this thread.

    WyoGrow Active Member

    Your take on watering and it depriving the root of oxygen is almost completely contrary to everything I have read, been taught and/or experienced myself. Now soil compaction facilitated by watering can and will smother roots. But that is in poorly structured high clay soils. And in this case it smothers the roots by not allowing the water to pass through the soil at a rate that will draw fresh air in behind it as it descends through the soil. Good growing mediums generally have good enough structure with components like perlite and sand to prevent heavy soil compaction. Soil drenching to the point of runoff is about the only way to get good air turnover in large planting containers. Not to mention prevents dry pockets in the growing medium that encourages salt buildup that can ultimately damage roots growing neat the dry area int he medium. Good soil structure is key though. If you have poorly structured, highly compactable soil then I agree. A large one time watering is harmful because it will compact the soil and not run off, becoming stagnant.
    Panda NYC

    Panda NYC New Member

    The runoff water is the final PH of the water absorbed by your plant. A lot of people find it less problematic because many cannabis plants have the capacity to grow between PH of 4.5 to 8.5 - this does not mean the plant is at its best. The best PH of runoff water should be between 5.6 to 6.
    cannakis and DrRonPaul2012 like this.

    hydroMD Well-Known Member

    I would be foolish to dispute your post, but for me it's simple. Giving your plants solutions that are properly Ph'd and then flushing once or twice during the cycle is enough.

    Thats just me, everyone should do whatever they feel they need to do to maximize their plants health.[/QUOTE]

    If your watering fast enough to send water cascading down the sides of your pot your doing it wrong!!!

    Soak the top layer of soil, leaving it sit for 10 min, then water. Soil will absorb the water instead of draining down the sides.

    Also, if your plant has a problem then check your runoff and adjust a little. If things look fine then your ph isn't swinging fast enough to negatively affect the plant.

    To say measuring runoff is useless is ridiculous. Plenty of info to be gathered to help isolate defeciencies

    hydroMD Well-Known Member

    Lol.... ok

    First off, if you do not have runoff you need to cut your ppm being added in half. Second, 4-8 times pot size for flushing?!?!?!?! Way overkill.

    3x pot size is all ya need with 10-20% nute mix. (Adding low ppms helps break down accumilated salts, like using oil based products to clean oil based stains)

    Also... testing your runoff when adding 8x your container size gives you ZERO info... only a washed out reading. The first 10ml-30ml runoffper gallon container size is what you want to test. ( 5 gal pot = 50-150 ml) give your pot a small pre soak to get the top layer of soil wet before u try to test to make sure your water is running through your soil.

    hydroMD Well-Known Member

    Roots organics will be low after watering and should slowly creep back up as it dries. If you start seeing defeciencies then adjust your ph a few points and wait a week to see results
    Panda NYC

    Panda NYC New Member

    Also I like to add some more insights, in case a lot of people go around and try to change the PH of their soil when it isn't necessary.

    First of, no reason to change the soil when runoff water PH is at 5.5 - it's a very good PH level. You only need to be alerted when the runoff water PH is less than 5 or higher than 7.5.

    Also if you are using organic fertilizers, the runoff water PH level matters less, because the nutrients are in a more complex form of compounds. The plant must decompose them before the using them during photosynthesis and respiration - therefore the level of charged ions will modified during the process of decomposition (usually to a mild and more plant-friendly level).

    Now, have you wondered why we recommend to water at PH of 5.6 to 6.0 for hydroponic growing and at PH of 6.2 to 6.5 for soil? You guess it right, because in a hydroponic environment, the PH level of the water will not change much after watering. The pH of pure water is related to the relative number of hydrogen and hydroxyl ions. If water has a higher proportion of hydrogen ions, it is acidic and has a pH less than 7. If it has a higher number of hydroxyl ions, then it is alkaline and has a pH of greater than 7. But water doesn't naturally exist without other mineral ions being present. In a soil environment, there are many free uncharged elements around, so they will take up the number of hydrogen or hydroxyl ions to form new chemical compounds - and these new compounds may be helpful or harmful to the plant depending on the original chemical compounds.

    When then original chemical compounds are simple compounds - usually found in non-organic nutrients like "GH bloom," etc, the PH level of runoff water represent an overall "helpfulness" of the new compounds absorbed by the plant. Therefore a PH level of 5.6 to 6.0 is optimal to the plant.

    That being said, PH level does not represent everything. You can have a very harmful environment while the PH level is optimal, while you can also have a very helpful environment while the PH level is very acidic or alkaline. BUT, if you want to take less risk, it's good to keep the PH level at optimal.
    DrRonPaul2012 and anzohaze like this.
    Panda NYC

    Panda NYC New Member

    Finally, the run-off water's PH level might not represent the overall PH level of the water being absorbed by the plant. This is because many chemical compounds will be flushed to the bottom of the pot after watering, therefore forming a particularly strong acidic or alkaline environment. The plant might be absorbing perfectly PH balanced water from other part of the soil in the pot, while the run-off water shows sign of significant acidic or alkaline level.
    anzohaze likes this.

    Pattahabi Well-Known Member

    Jesus... Reading plant runoff tells you nothing!

    :: shakes head ::

    Stink Bug, greasemonkeymann and Rrog like this.

    Zzyphr Member

    Ran across this old thread while searching this exact question. In my case, the plant is showing signs of distress. I decided to check the outgoing and it was horribly low. Extreme measures are begining to show progress. For me, checking the outflow pH let you know what the plant is taking from the soil and nutrients administered. So if you have a baseline early, then you can get a coarse understanding if the plant needs more nutrients, not less - as well as maintaining soil pH.
    One negative outcome is the quicker destruction of your pH sensor, but such are the costs of a wonderful hobby.

    @ Dr. Greener
    Voice of reason and respect. Thank you.

    cannakis Well-Known Member

    That's not necessarily true... Because different characteristics of your bowel movements Do indicate too little or too much of certain nutrients... And you can definitely see that fake yellow corn.
    DrRonPaul2012 likes this.

    cannakis Well-Known Member

    How can you say that? There is definitely Something to be said about the runoff, it can tell certain things, its not like you are testing something completely different, it still pertains to that specific plant and pot.

    Nullis Moderator

    It tells you more than nothing but less than everything, which for most intents and purposes happens to be just more than enough.

    By which I mean it certainly can be interpreted as providing some clue that things aren't wildly out of whack. Provided that you water slowly, know the pH of the water source (ideally its near neutral), and discard the first oz or two of the runoff.
    cannakis likes this.

    cannakis Well-Known Member


    GrNAppLeQcKSteP Member


    Rrog Well-Known Member

    Firstly, adding "nutes," regardless of the label immediately puts the whole natural plant / microbe relationship into question.

    Secondly, if the aforementioned relationship is allowed to happen, the plant and microbes determine the soil pH, regardless of your "pH balancing" the water. Measuring pH can be fun, but not necessary.

    If someone's bottle-feeding plants, and using some sorta soil as a grow medium, then maybe there would be value in measuring pH. This is sort of a hybrid soil / hydro thing. No idea what's going on in there
    greasemonkeymann likes this.

    greasemonkeymann Well-Known Member

    thank you!!!
    If you are into flushing, salts, ppms, and PH, you should check out the whole growing with chemicals thing.
    if you have even 50% of the grasp on organics you won't need a ph tester at all.
    And flushing?
    I won't even dignify that one with a response.
    might as well be buying superthrive and carb boosters to go with your 0-50-50 bloom ferts
    GoRealUhGro, Pattahabi and Rrog like this.

    cannakis Well-Known Member

    Haha did I even say flushing? Again I have to disagree that pH does matter... But also agree that I Should Have Fucking Listened! Haha but I have learned more than I ever thought from said foolishness.!

    Speaking of... I'm losing girls left and right because I top them to clone the seed stock and they have like No leaves except 4fans and the nodes, and I water too much sometimes thinking I didn't, and kill it! And my clones are taking forever!!!

    Haha honestly I think it was is due to my "pH"ing the water which fresh rain water by adding ACV and I think I should have left it alone! Man I'm a fool.!. I always think I can reinvent the wheel, and want Everyone to know "my" opinion.!
    Rrog likes this.

    greasemonkeymann Well-Known Member

    ahhh man, gotta love ya brother.
    I don't know what to say man
    cannakis likes this.

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