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Soil ph won't go down despite water ph adjustments

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    HELP! Soil ph won't go down despite water ph adjustments

    I am growing two plants in Roots Organics soil. Despite using GH Ph Up and Down to adjust the ph of my water (typically 6.1-6.3), my soil ph still registers 7.0. Further, my runoff is high as well (6.8-7.0). Has anyone else experienced this? I use tap water and let it sit overnight before adjusting the ph prior to watering. I am using Soul Synthetics and Roots Organics for nutes/supplements and always adjust the ph on those just before watering.

    One of my plants definitely looks like there has been some nutrient lockout going on (magnesium and nitrogen deficiencies), but the other one seems to be handling the slightly higher ph much better.

    My inclination is to do the obvious thing and reduce the ph of my water even further, maybe 5.5-5.8, but I don't want to cause any additional harm to my ladies.

    I am in week 8 of flower. I used a foliar application of epsom salts to try to halt the mg deficiency. Pics can be provided if necessary, but I'm more curious about the ph issue than diagnosing the plants.

    Let me know if you need further details.


    Is your meter working right ,or are you using drops ?


      I am using a Dr. Meter ph tester (the standard yellow one that seems to be popular). It responds to me using GH PH Up and Down the way I think it should. I also use it to brew beer and have never had an issue.


        Is use meters to ,but I also check with drops just as a backup, how long are you letting your water stabilize before checking PH after adding up or down? Meters can act funny sometimes.


          Interesting point, I hadn't considered that. I don't let it sit for long at all. I typically put the drops in (usually Up when using nutes, Down when just using water) and test it again almost immediately.

          When I am testing the soil, I mix a 1:2 ratio of soil to distilled water and let that sit for 10-20 minutes before checking it.

          Is there a recommended time to wait after adding the Up/Down?

          I used the drops during the veg stage, but I got sick of the constant pour, check, adjust, repeat routine since I had a ph meter lying around anyway.

          Thanks again for the response.


            Add aluminum sulfate to ur soil when u transplant


              This will bring ur soil ph level down


                Whim I usually wait at least 30 minutes ,don't know what everyone else does, I use Earth Juice crystals and it takes a while to settle. Good luck.


                  i think i know whats going on, when ever you put nutes in your water the ph goes down cause most nutrients have positive ions in them and water has not much at all, so you put ph up in there witch is made with negative ions and your reading shows a balanced ph but when the plant uses the nutrients those negative ions remain in your soil, you could say you have a ph up "build up". when you water with just water (almost no ions) this rarely changes the ph of the soil (balance of ions), even with some ph down a few positive ions are enough to counter act the little negative ones in the water but not the bunch you have in the soil. so very low ppm has a volatile ph and does not changes the soil ph's, very high ppm water has a very stable ph and has huge impact on soil ph,

                  SOLUTION: if your soil has too high ph then flush with plain water (low ppm, ph doesnt really matter) to leach anything building up in the medium, the plain water witll immediately disolve whats in the soil and comes out with the ph of the SOIL. this way you can know when you flushed enough. Then the next feeding adjust the ph of the water and nutrients at 6 until runoff gets around 6.5 then keep watering with 6.5 ph.
                  you may need to repeat this a couple of times to get it stable, heres a ph chart to get your head around this
                  Click image for larger version

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                  granddaddy purple journal


                    Excellent advice, everyone. Thanks!


                      In case anyone is still interested in this topic, I believe I may have found the culprit. From the Aurora website:

                      Our heavy organic soils have a buffering capacity, to which you can add nutrients (according to our “feeding schedules”) without adjusting the pH. The buffering capacity of the soil will regulate the pH of the soil solution, so that necessary micro and macro nutrients will become available. If you prefer to have more control over the pH of your solution, we recommend adjusting the pH to 5.8-6.3. When in doubt... err on the side of acidic.

                      That pretty much sums it up. For the entire vegetation stage and the first half of flower, I was adjusting the ph to 6.3-6.5 or so. My plants were far more resilient in the veg stage, so they didn't show any nutrient lock-out until the switch to flower. Since then, I did some flushing on both ladies and have been adjusting to around 5.8-6.1 with significantly more success. Both plants are looking beautiful.

                      Thanks again for the suggestions.


                        🌱 Please let us know how it goes! Also, I noticed you said you're using PH Up and Down. I'm not sure if you meant at the same time. If possible, try to only use one at a time when mixing nutrients. Just give a tiny bit at a time so you don't overshoot. Also, it can help to let the water sit out, and make sure to always pH after the nutrients have been added. You're already at week 8 so you're doing great! They get a lot more sensitive after week 6 or so, so it's normal to struggle a little at this stage! If possible, feel free to post a picture of the plant in the setup and we might have other suggestions! It sounds like you talked to the nutrient company, and they'll know better than anyone so thanks for sharing what they said! 🌱
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